From c59e6d4af2d2cbaf38282218324b973370502280 Mon Sep 17 00:00:00 2001
From: Phil Davis <phil@jankaritech.com>
Date: Mon, 6 Jan 2025 14:14:03 +0545
Subject: [PATCH 1/5] chore: update to phpstan major version 2

---
 composer.json                  | 7 +++++--
 lib/Message.php                | 5 +----
 lib/Sapi.php                   | 2 +-
 phpstan.neon                   | 8 ++++++++
 tests/HTTP/Auth/AWSTest.php    | 2 +-
 tests/HTTP/Auth/DigestTest.php | 2 +-
 tests/HTTP/RequestTest.php     | 2 +-
 7 files changed, 18 insertions(+), 10 deletions(-)

diff --git a/composer.json b/composer.json
index 80c9daa..d3768ad 100644
--- a/composer.json
+++ b/composer.json
@@ -13,8 +13,11 @@
         "sabre/uri"    : "^2.3"
     },
     "require-dev" : {
-        "friendsofphp/php-cs-fixer": "^3.87",
-        "phpstan/phpstan": "^1.12",
+        "friendsofphp/php-cs-fixer": "^3.95",
+        "phpstan/phpstan": "^2.1",
+        "phpstan/phpstan-phpunit": "^2.0",
+        "phpstan/phpstan-strict-rules": "^2.0",
+        "phpstan/extension-installer": "^1.4",
         "phpunit/phpunit" : "^9.6"
     },
     "suggest" : {
diff --git a/lib/Message.php b/lib/Message.php
index a999999..201458c 100644
--- a/lib/Message.php
+++ b/lib/Message.php
@@ -82,11 +82,8 @@ public function getBodyAsString(): string
 
             return ob_get_clean();
         }
-        /**
-         * @var string|int|null $contentLength
-         */
         $contentLength = $this->getHeader('Content-Length');
-        if (null !== $contentLength && (is_int($contentLength) || ctype_digit($contentLength))) {
+        if (null !== $contentLength && ctype_digit($contentLength)) {
             return stream_get_contents($body, (int) $contentLength);
         }
 
diff --git a/lib/Sapi.php b/lib/Sapi.php
index b37c023..d1a5065 100644
--- a/lib/Sapi.php
+++ b/lib/Sapi.php
@@ -86,7 +86,7 @@ public static function sendResponse(ResponseInterface $response): void
         $contentLength = $response->getHeader('Content-Length');
         if (null !== $contentLength) {
             $output = fopen('php://output', 'wb');
-            if (is_resource($body) && 'stream' == get_resource_type($body)) {
+            if (is_resource($body) && 'stream' === get_resource_type($body)) {
                 // a workaround to make PHP more possible to use mmap based copy, see https://github.com/sabre-io/http/pull/119
                 $left = (int) $contentLength;
                 // copy with 4MiB chunks
diff --git a/phpstan.neon b/phpstan.neon
index 5802f6f..25979fe 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -14,6 +14,14 @@ parameters:
     message: "#^Left side of || is always false.$#"
     count: 2
     path: lib/Client.php
+  -
+    message: "#^Strict comparison using !== between '' and non-empty-string will always evaluate to true.$#"
+    count: 1
+    path: lib/Auth/Digest.php
+  -
+    message: "#^Casting to string something that's already string.$#"
+    count: 1
+    path: lib/Sapi.php
   -
     message: "#^Strict comparison using === between null and array<string, mixed> will always evaluate to false.$#"
     count: 1
diff --git a/tests/HTTP/Auth/AWSTest.php b/tests/HTTP/Auth/AWSTest.php
index 0999c95..4e266ae 100644
--- a/tests/HTTP/Auth/AWSTest.php
+++ b/tests/HTTP/Auth/AWSTest.php
@@ -200,7 +200,7 @@ public function test401(): void
     {
         $this->auth->requireLogin();
         $test = preg_match('/^AWS$/', $this->response->getHeader('WWW-Authenticate'), $matches);
-        $this->assertTrue(true == $test, 'The WWW-Authenticate response didn\'t match our pattern');
+        self::assertTrue(1 === $test, 'The WWW-Authenticate response didn\'t match our pattern');
     }
 
     /**
diff --git a/tests/HTTP/Auth/DigestTest.php b/tests/HTTP/Auth/DigestTest.php
index dbc9416..13bfae5 100644
--- a/tests/HTTP/Auth/DigestTest.php
+++ b/tests/HTTP/Auth/DigestTest.php
@@ -166,7 +166,7 @@ private function getServerTokens(int $qop = Digest::QOP_AUTH): array
         $test = preg_match('/Digest realm="'.self::REALM.'",qop="'.$qopstr.'",nonce="([0-9a-f]*)",opaque="([0-9a-f]*)"/',
             $this->response->getHeader('WWW-Authenticate'), $matches);
 
-        $this->assertTrue(true == $test, 'The WWW-Authenticate response didn\'t match our pattern. We received: '.$this->response->getHeader('WWW-Authenticate'));
+        self::assertTrue(1 === $test, 'The WWW-Authenticate response didn\'t match our pattern. We received: '.$this->response->getHeader('WWW-Authenticate'));
 
         $nonce = $matches[1];
         $opaque = $matches[2];
diff --git a/tests/HTTP/RequestTest.php b/tests/HTTP/RequestTest.php
index 2a7432a..d1a8644 100644
--- a/tests/HTTP/RequestTest.php
+++ b/tests/HTTP/RequestTest.php
@@ -35,7 +35,7 @@ public function testGetQueryParametersNoData(): void
     }
 
     /**
-     * @backupGlobals
+     * @backupGlobals enabled
      */
     public function testCreateFromPHPRequest(): void
     {

From 6a036f0d8a4fdcafb305647b529a49d65ad08027 Mon Sep 17 00:00:00 2001
From: Phil Davis <phil@jankaritech.com>
Date: Mon, 6 Jan 2025 17:15:32 +0545
Subject: [PATCH 2/5] chore: remove phpVersion from phpstan.neon

---
 phpstan.neon | 1 -
 1 file changed, 1 deletion(-)

diff --git a/phpstan.neon b/phpstan.neon
index 25979fe..fd45673 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,6 +1,5 @@
 parameters:
   level: 6
-  phpVersion: 70430 # PHP 7.4.30
   ignoreErrors:
   -
     message: "#^Negated boolean expression is always true.$#"

From 1d1839b950354b403a06777b865c4b136409ce0b Mon Sep 17 00:00:00 2001
From: Phil Davis <phil@jankaritech.com>
Date: Mon, 6 Jan 2025 17:53:49 +0545
Subject: [PATCH 3/5] chore: update ignoreErrrors count

---
 phpstan.neon | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/phpstan.neon b/phpstan.neon
index fd45673..5e58410 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -11,7 +11,7 @@ parameters:
     path: lib/Client.php
   -
     message: "#^Left side of || is always false.$#"
-    count: 2
+    count: 19
     path: lib/Client.php
   -
     message: "#^Strict comparison using !== between '' and non-empty-string will always evaluate to true.$#"

From 2e6fd93ea9f2711e101e50b59c7712239fdc4399 Mon Sep 17 00:00:00 2001
From: Phillip Davis <phil@jankaritech.com>
Date: Mon, 27 Apr 2026 16:07:43 +0930
Subject: [PATCH 4/5] chore: implement different phpstan ignore by PHP version

---
 phpstan-ignore-by-php-version.neon.php | 18 ++++++++++++++++++
 phpstan-ignore-php74.neon              |  6 ++++++
 phpstan-ignore-php8.neon               |  6 ++++++
 phpstan.neon                           | 15 +++------------
 4 files changed, 33 insertions(+), 12 deletions(-)
 create mode 100644 phpstan-ignore-by-php-version.neon.php
 create mode 100644 phpstan-ignore-php74.neon
 create mode 100644 phpstan-ignore-php8.neon

diff --git a/phpstan-ignore-by-php-version.neon.php b/phpstan-ignore-by-php-version.neon.php
new file mode 100644
index 0000000..5f58a1c
--- /dev/null
+++ b/phpstan-ignore-by-php-version.neon.php
@@ -0,0 +1,18 @@
+<?php
+
+declare(strict_types=1);
+
+$includes = [];
+if (PHP_VERSION_ID >= 80000) {
+    $includes[] = __DIR__.'/phpstan-ignore-php8.neon';
+} else {
+    $includes[] = __DIR__.'/phpstan-ignore-php74.neon';
+}
+
+$config = [];
+$config['includes'] = $includes;
+
+// overrides config.platform.php in composer.json
+$config['parameters']['phpVersion'] = PHP_VERSION_ID;
+
+return $config;
diff --git a/phpstan-ignore-php74.neon b/phpstan-ignore-php74.neon
new file mode 100644
index 0000000..041b324
--- /dev/null
+++ b/phpstan-ignore-php74.neon
@@ -0,0 +1,6 @@
+parameters:
+  ignoreErrors:
+  -
+    message: "#^Left side of || is always false.$#"
+    count: 10
+    path: lib/Client.php
diff --git a/phpstan-ignore-php8.neon b/phpstan-ignore-php8.neon
new file mode 100644
index 0000000..43b26f0
--- /dev/null
+++ b/phpstan-ignore-php8.neon
@@ -0,0 +1,6 @@
+parameters:
+  ignoreErrors:
+  -
+    message: "#^Left side of || is always false.$#"
+    count: 23
+    path: lib/Client.php
diff --git a/phpstan.neon b/phpstan.neon
index 5e58410..52d9ac3 100644
--- a/phpstan.neon
+++ b/phpstan.neon
@@ -1,18 +1,9 @@
+includes:
+  - phpstan-ignore-by-php-version.neon.php
+
 parameters:
   level: 6
   ignoreErrors:
-  -
-    message: "#^Negated boolean expression is always true.$#"
-    count: 1
-    path: lib/Client.php
-  -
-    message: "#^If condition is always false.$#"
-    count: 3
-    path: lib/Client.php
-  -
-    message: "#^Left side of || is always false.$#"
-    count: 19
-    path: lib/Client.php
   -
     message: "#^Strict comparison using !== between '' and non-empty-string will always evaluate to true.$#"
     count: 1

From c76b861017f6f797f13590e42f349868ede7ad6c Mon Sep 17 00:00:00 2001
From: Phil Davis <phil@jankaritech.com>
Date: Wed, 8 Feb 2023 17:57:54 +0545
Subject: [PATCH 5/5] test: Call static assert functions with self::

---
 tests/HTTP/Auth/AWSTest.php          | 30 ++++-----
 tests/HTTP/Auth/BasicTest.php        | 12 ++--
 tests/HTTP/Auth/BearerTest.php       | 10 +--
 tests/HTTP/Auth/DigestTest.php       | 16 ++---
 tests/HTTP/ClientTest.php            | 96 ++++++++++++++--------------
 tests/HTTP/FunctionsTest.php         | 14 ++--
 tests/HTTP/MessageDecoratorTest.php  | 52 +++++++--------
 tests/HTTP/MessageTest.php           | 62 +++++++++---------
 tests/HTTP/NegotiateTest.php         |  2 +-
 tests/HTTP/RequestDecoratorTest.php  | 38 +++++------
 tests/HTTP/RequestTest.php           | 28 ++++----
 tests/HTTP/ResponseDecoratorTest.php | 10 +--
 tests/HTTP/ResponseTest.php          | 14 ++--
 tests/HTTP/SapiTest.php              | 44 ++++++-------
 tests/HTTP/URLUtilTest.php           | 22 +++----
 15 files changed, 225 insertions(+), 225 deletions(-)

diff --git a/tests/HTTP/Auth/AWSTest.php b/tests/HTTP/Auth/AWSTest.php
index 4e266ae..f9ac27f 100644
--- a/tests/HTTP/Auth/AWSTest.php
+++ b/tests/HTTP/Auth/AWSTest.php
@@ -29,8 +29,8 @@ public function testNoHeader(): void
         $this->request->setMethod('GET');
         $result = $this->auth->init();
 
-        $this->assertFalse($result, 'No AWS Authorization header was supplied, so we should have gotten false');
-        $this->assertEquals(AWS::ERR_NOAWSHEADER, $this->auth->errorCode);
+        self::assertFalse($result, 'No AWS Authorization header was supplied, so we should have gotten false');
+        self::assertEquals(AWS::ERR_NOAWSHEADER, $this->auth->errorCode);
     }
 
     public function testInvalidAuthorizationHeader(): void
@@ -38,7 +38,7 @@ public function testInvalidAuthorizationHeader(): void
         $this->request->setMethod('GET');
         $this->request->setHeader('Authorization', 'Invalid Auth Header');
 
-        $this->assertFalse($this->auth->init(), 'The Invalid AWS authorization header');
+        self::assertFalse($this->auth->init(), 'The Invalid AWS authorization header');
     }
 
     public function testIncorrectContentMD5(): void
@@ -56,8 +56,8 @@ public function testIncorrectContentMD5(): void
         $this->auth->init();
         $result = $this->auth->validate($secretKey);
 
-        $this->assertFalse($result);
-        $this->assertEquals(AWS::ERR_MD5CHECKSUMWRONG, $this->auth->errorCode);
+        self::assertFalse($result);
+        self::assertEquals(AWS::ERR_MD5CHECKSUMWRONG, $this->auth->errorCode);
     }
 
     public function testNoDate(): void
@@ -78,8 +78,8 @@ public function testNoDate(): void
         $this->auth->init();
         $result = $this->auth->validate($secretKey);
 
-        $this->assertFalse($result);
-        $this->assertEquals(AWS::ERR_INVALIDDATEFORMAT, $this->auth->errorCode);
+        self::assertFalse($result);
+        self::assertEquals(AWS::ERR_INVALIDDATEFORMAT, $this->auth->errorCode);
     }
 
     public function testFutureDate(): void
@@ -105,8 +105,8 @@ public function testFutureDate(): void
         $this->auth->init();
         $result = $this->auth->validate($secretKey);
 
-        $this->assertFalse($result);
-        $this->assertEquals(AWS::ERR_REQUESTTIMESKEWED, $this->auth->errorCode);
+        self::assertFalse($result);
+        self::assertEquals(AWS::ERR_REQUESTTIMESKEWED, $this->auth->errorCode);
     }
 
     public function testPastDate(): void
@@ -132,8 +132,8 @@ public function testPastDate(): void
         $this->auth->init();
         $result = $this->auth->validate($secretKey);
 
-        $this->assertFalse($result);
-        $this->assertEquals(AWS::ERR_REQUESTTIMESKEWED, $this->auth->errorCode);
+        self::assertFalse($result);
+        self::assertEquals(AWS::ERR_REQUESTTIMESKEWED, $this->auth->errorCode);
     }
 
     public function testIncorrectSignature(): void
@@ -160,8 +160,8 @@ public function testIncorrectSignature(): void
         $this->auth->init();
         $result = $this->auth->validate($secretKey);
 
-        $this->assertFalse($result);
-        $this->assertEquals(AWS::ERR_INVALIDSIGNATURE, $this->auth->errorCode);
+        self::assertFalse($result);
+        self::assertEquals(AWS::ERR_INVALIDSIGNATURE, $this->auth->errorCode);
     }
 
     public function testValidRequest(): void
@@ -192,8 +192,8 @@ public function testValidRequest(): void
         $this->auth->init();
         $result = $this->auth->validate($secretKey);
 
-        $this->assertTrue($result, 'Signature did not validate, got errorcode '.$this->auth->errorCode);
-        $this->assertEquals($accessKey, $this->auth->getAccessKey());
+        self::assertTrue($result, 'Signature did not validate, got errorcode '.$this->auth->errorCode);
+        self::assertEquals($accessKey, $this->auth->getAccessKey());
     }
 
     public function test401(): void
diff --git a/tests/HTTP/Auth/BasicTest.php b/tests/HTTP/Auth/BasicTest.php
index 9b10381..7819528 100644
--- a/tests/HTTP/Auth/BasicTest.php
+++ b/tests/HTTP/Auth/BasicTest.php
@@ -17,7 +17,7 @@ public function testGetCredentials(): void
 
         $basic = new Basic('Dagger', $request, new Response());
 
-        $this->assertEquals([
+        self::assertEquals([
             'user',
             'pass:bla',
         ], $basic->getCredentials());
@@ -31,7 +31,7 @@ public function testGetInvalidCredentialsColonMissing(): void
 
         $basic = new Basic('Dagger', $request, new Response());
 
-        $this->assertNull($basic->getCredentials());
+        self::assertNull($basic->getCredentials());
     }
 
     public function testGetCredentialsNoHeader(): void
@@ -39,7 +39,7 @@ public function testGetCredentialsNoHeader(): void
         $request = new Request('GET', '/', []);
         $basic = new Basic('Dagger', $request, new Response());
 
-        $this->assertNull($basic->getCredentials());
+        self::assertNull($basic->getCredentials());
     }
 
     public function testGetCredentialsNotBasic(): void
@@ -49,7 +49,7 @@ public function testGetCredentialsNotBasic(): void
         ]);
         $basic = new Basic('Dagger', $request, new Response());
 
-        $this->assertNull($basic->getCredentials());
+        self::assertNull($basic->getCredentials());
     }
 
     public function testRequireLogin(): void
@@ -61,7 +61,7 @@ public function testRequireLogin(): void
 
         $basic->requireLogin();
 
-        $this->assertEquals('Basic realm="Dagger", charset="UTF-8"', $response->getHeader('WWW-Authenticate'));
-        $this->assertEquals(401, $response->getStatus());
+        self::assertEquals('Basic realm="Dagger", charset="UTF-8"', $response->getHeader('WWW-Authenticate'));
+        self::assertEquals(401, $response->getStatus());
     }
 }
diff --git a/tests/HTTP/Auth/BearerTest.php b/tests/HTTP/Auth/BearerTest.php
index d21f23d..22df027 100644
--- a/tests/HTTP/Auth/BearerTest.php
+++ b/tests/HTTP/Auth/BearerTest.php
@@ -17,7 +17,7 @@ public function testGetToken(): void
 
         $bearer = new Bearer('Dagger', $request, new Response());
 
-        $this->assertEquals(
+        self::assertEquals(
             '12345',
             $bearer->getToken()
         );
@@ -28,7 +28,7 @@ public function testGetCredentialsNoHeader(): void
         $request = new Request('GET', '/', []);
         $bearer = new Bearer('Dagger', $request, new Response());
 
-        $this->assertNull($bearer->getToken());
+        self::assertNull($bearer->getToken());
     }
 
     public function testGetCredentialsNotBearer(): void
@@ -38,7 +38,7 @@ public function testGetCredentialsNotBearer(): void
         ]);
         $bearer = new Bearer('Dagger', $request, new Response());
 
-        $this->assertNull($bearer->getToken());
+        self::assertNull($bearer->getToken());
     }
 
     public function testRequireLogin(): void
@@ -49,7 +49,7 @@ public function testRequireLogin(): void
 
         $bearer->requireLogin();
 
-        $this->assertEquals('Bearer realm="Dagger"', $response->getHeader('WWW-Authenticate'));
-        $this->assertEquals(401, $response->getStatus());
+        self::assertEquals('Bearer realm="Dagger"', $response->getHeader('WWW-Authenticate'));
+        self::assertEquals(401, $response->getStatus());
     }
 }
diff --git a/tests/HTTP/Auth/DigestTest.php b/tests/HTTP/Auth/DigestTest.php
index 13bfae5..f5bc609 100644
--- a/tests/HTTP/Auth/DigestTest.php
+++ b/tests/HTTP/Auth/DigestTest.php
@@ -50,10 +50,10 @@ public function testDigest(): void
 
         $this->auth->init();
 
-        $this->assertEquals($username, $this->auth->getUsername());
-        $this->assertEquals(self::REALM, $this->auth->getRealm());
-        $this->assertTrue($this->auth->validateA1(md5($username.':'.self::REALM.':'.$password)), 'Authentication is deemed invalid through validateA1');
-        $this->assertTrue($this->auth->validatePassword($password), 'Authentication is deemed invalid through validatePassword');
+        self::assertEquals($username, $this->auth->getUsername());
+        self::assertEquals(self::REALM, $this->auth->getRealm());
+        self::assertTrue($this->auth->validateA1(md5($username.':'.self::REALM.':'.$password)), 'Authentication is deemed invalid through validateA1');
+        self::assertTrue($this->auth->validatePassword($password), 'Authentication is deemed invalid through validatePassword');
     }
 
     public function testInvalidDigest(): void
@@ -79,7 +79,7 @@ public function testInvalidDigest(): void
 
         $this->auth->init();
 
-        $this->assertFalse($this->auth->validateA1(md5($username.':'.self::REALM.':'.($password.'randomness'))), 'Authentication is deemed invalid through validateA1');
+        self::assertFalse($this->auth->validateA1(md5($username.':'.self::REALM.':'.($password.'randomness'))), 'Authentication is deemed invalid through validateA1');
     }
 
     public function testInvalidDigest2(): void
@@ -88,7 +88,7 @@ public function testInvalidDigest2(): void
         $this->request->setHeader('Authorization', 'basic blablabla');
 
         $this->auth->init();
-        $this->assertFalse($this->auth->validateA1(md5('user:realm:password')));
+        self::assertFalse($this->auth->validateA1(md5('user:realm:password')));
     }
 
     public function testDigestAuthInt(): void
@@ -116,7 +116,7 @@ public function testDigestAuthInt(): void
 
         $this->auth->init();
 
-        $this->assertTrue($this->auth->validateA1(md5($username.':'.self::REALM.':'.$password)), 'Authentication is deemed invalid through validateA1');
+        self::assertTrue($this->auth->validateA1(md5($username.':'.self::REALM.':'.$password)), 'Authentication is deemed invalid through validateA1');
     }
 
     public function testDigestAuthBoth(): void
@@ -144,7 +144,7 @@ public function testDigestAuthBoth(): void
 
         $this->auth->init();
 
-        $this->assertTrue($this->auth->validateA1(md5($username.':'.self::REALM.':'.$password)), 'Authentication is deemed invalid through validateA1');
+        self::assertTrue($this->auth->validateA1(md5($username.':'.self::REALM.':'.$password)), 'Authentication is deemed invalid through validateA1');
     }
 
     /**
diff --git a/tests/HTTP/ClientTest.php b/tests/HTTP/ClientTest.php
index 0c264cf..9fe3d04 100644
--- a/tests/HTTP/ClientTest.php
+++ b/tests/HTTP/ClientTest.php
@@ -48,7 +48,7 @@ public function testCreateCurlSettingsArrayGET(): void
             CURLOPT_USERAGENT => 'sabre-http/'.Version::VERSION.' (http://sabre.io/)',
         ] + self::protocolSettings();
 
-        $this->assertEquals($settings, $client->createCurlSettingsArray($request));
+        self::assertEquals($settings, $client->createCurlSettingsArray($request));
     }
 
     public function testCreateCurlSettingsHTTPHeader(): void
@@ -91,7 +91,7 @@ public function testCreateCurlSettingsArrayHEAD(): void
             CURLOPT_USERAGENT => 'sabre-http/'.Version::VERSION.' (http://sabre.io/)',
         ] + self::protocolSettings();
 
-        $this->assertEquals($settings, $client->createCurlSettingsArray($request));
+        self::assertEquals($settings, $client->createCurlSettingsArray($request));
     }
 
     public function testCreateCurlSettingsArrayGETAfterHEAD(): void
@@ -117,7 +117,7 @@ public function testCreateCurlSettingsArrayGETAfterHEAD(): void
             CURLOPT_USERAGENT => 'sabre-http/'.Version::VERSION.' (http://sabre.io/)',
         ] + self::protocolSettings();
 
-        $this->assertEquals($settings, $client->createCurlSettingsArray($request));
+        self::assertEquals($settings, $client->createCurlSettingsArray($request));
     }
 
     public function testCreateCurlSettingsArrayPUTStream(): void
@@ -142,7 +142,7 @@ public function testCreateCurlSettingsArrayPUTStream(): void
             CURLOPT_USERAGENT => 'sabre-http/'.Version::VERSION.' (http://sabre.io/)',
         ] + self::protocolSettings();
 
-        $this->assertEquals($settings, $client->createCurlSettingsArray($request));
+        self::assertEquals($settings, $client->createCurlSettingsArray($request));
     }
 
     public function testCreateCurlSettingsArrayPUTString(): void
@@ -161,7 +161,7 @@ public function testCreateCurlSettingsArrayPUTString(): void
             CURLOPT_USERAGENT => 'sabre-http/'.Version::VERSION.' (http://sabre.io/)',
         ] + self::protocolSettings();
 
-        $this->assertEquals($settings, $client->createCurlSettingsArray($request));
+        self::assertEquals($settings, $client->createCurlSettingsArray($request));
     }
 
     public function testIssue89MultiplePutInfileGivesWarning(): void
@@ -171,20 +171,20 @@ public function testIssue89MultiplePutInfileGivesWarning(): void
         $request = new Request('POST', 'http://example.org/', ['X-Foo' => 'bar'], 'body');
 
         $settings = $client->createCurlSettingsArray($request);
-        $this->assertArrayNotHasKey(CURLOPT_PUT, $settings);
-        $this->assertArrayNotHasKey(CURLOPT_INFILE, $settings);
+        self::assertArrayNotHasKey(CURLOPT_PUT, $settings);
+        self::assertArrayNotHasKey(CURLOPT_INFILE, $settings);
 
         $request = new Request('POST', 'http://example.org/', ['X-Foo' => 'bar'], $tmpFile);
 
         $settings = $client->createCurlSettingsArray($request);
-        $this->assertEquals(true, $settings[CURLOPT_PUT]);
-        $this->assertEquals($tmpFile, $settings[CURLOPT_INFILE]);
+        self::assertEquals(true, $settings[CURLOPT_PUT]);
+        self::assertEquals($tmpFile, $settings[CURLOPT_INFILE]);
 
         $request = new Request('POST', 'http://example.org/', ['X-Foo' => 'bar'], 'body');
 
         $settings = $client->createCurlSettingsArray($request);
-        $this->assertArrayNotHasKey(CURLOPT_PUT, $settings);
-        $this->assertArrayNotHasKey(CURLOPT_INFILE, $settings);
+        self::assertArrayNotHasKey(CURLOPT_PUT, $settings);
+        self::assertArrayNotHasKey(CURLOPT_INFILE, $settings);
     }
 
     public function testSend(): void
@@ -198,7 +198,7 @@ public function testSend(): void
 
         $response = $client->send($request);
 
-        $this->assertEquals(200, $response->getStatus());
+        self::assertEquals(200, $response->getStatus());
     }
 
     /**
@@ -238,8 +238,8 @@ public function testSendToGetLargeContent(): void
         $client = new Client();
         $response = $client->send($request);
 
-        $this->assertEquals(200, $response->getStatus());
-        $this->assertLessThan(
+        self::assertEquals(200, $response->getStatus());
+        self::assertLessThan(
             (int) $maxPeakMemoryUsage,
             memory_get_peak_usage(),
             "Hint: you can adjust the max peak memory usage allowed for this test by defining env variable $maxPeakMemoryUsageEnvVariable to be the desired max bytes"
@@ -260,9 +260,9 @@ public function testSendAsync(): void
 
         $request = new Request('GET', $url);
         $client->sendAsync($request, function (ResponseInterface $response) {
-            $this->assertEquals("foo\n", $response->getBody());
-            $this->assertEquals(200, $response->getStatus());
-            $this->assertEquals(4, $response->getHeader('Content-Length'));
+            self::assertEquals("foo\n", $response->getBody());
+            self::assertEquals(200, $response->getStatus());
+            self::assertEquals(4, $response->getHeader('Content-Length'));
         }, function ($error) use ($request) {
             $url = $request->getUrl();
             $this->fail("Failed to GET $url");
@@ -285,9 +285,9 @@ public function testSendAsynConsecutively(): void
 
         $request = new Request('GET', $url);
         $client->sendAsync($request, function (ResponseInterface $response) {
-            $this->assertEquals("foo\n", $response->getBody());
-            $this->assertEquals(200, $response->getStatus());
-            $this->assertEquals(4, $response->getHeader('Content-Length'));
+            self::assertEquals("foo\n", $response->getBody());
+            self::assertEquals(200, $response->getStatus());
+            self::assertEquals(4, $response->getHeader('Content-Length'));
         }, function ($error) use ($request) {
             $url = $request->getUrl();
             $this->fail("Failed to get $url");
@@ -296,9 +296,9 @@ public function testSendAsynConsecutively(): void
         $url = $this->getAbsoluteUrl('/bar.php');
         $request = new Request('GET', $url);
         $client->sendAsync($request, function (ResponseInterface $response) {
-            $this->assertEquals("bar\n", $response->getBody());
-            $this->assertEquals(200, $response->getStatus());
-            $this->assertEquals('Bar', $response->getHeader('X-Test'));
+            self::assertEquals("bar\n", $response->getBody());
+            self::assertEquals(200, $response->getStatus());
+            self::assertEquals('Bar', $response->getHeader('X-Test'));
         }, function ($error) use ($request) {
             $url = $request->getUrl();
             $this->fail("Failed to get $url");
@@ -325,7 +325,7 @@ public function testSendClientError(): void
             $this->fail('send() should have thrown an exception');
         } catch (ClientException $e) {
         }
-        $this->assertTrue($called);
+        self::assertTrue($called);
     }
 
     public function testSendHttpError(): void
@@ -345,7 +345,7 @@ public function testSendHttpError(): void
         });
 
         $client->send($request);
-        $this->assertEquals(2, $called);
+        self::assertEquals(2, $called);
     }
 
     public function testSendRetry(): void
@@ -370,9 +370,9 @@ public function testSendRetry(): void
         });
 
         $response = $client->send($request);
-        $this->assertEquals(3, $called);
-        $this->assertEquals(2, $errorCalled);
-        $this->assertEquals(200, $response->getStatus());
+        self::assertEquals(3, $called);
+        self::assertEquals(2, $errorCalled);
+        self::assertEquals(200, $response->getStatus());
     }
 
     public function testHttpErrorException(): void
@@ -389,8 +389,8 @@ public function testHttpErrorException(): void
             $client->send($request);
             $this->fail('An exception should have been thrown');
         } catch (ClientHttpException $e) {
-            $this->assertEquals(404, $e->getHttpStatus());
-            $this->assertInstanceOf('Sabre\HTTP\Response', $e->getResponse());
+            self::assertEquals(404, $e->getHttpStatus());
+            self::assertInstanceOf('Sabre\HTTP\Response', $e->getResponse());
         }
     }
 
@@ -412,11 +412,11 @@ public function testParseCurlResult(): void
         /** @phpstan-ignore-next-line */
         $result = $client->parseCurlResult($body, 'foobar');
 
-        $this->assertEquals(Client::STATUS_SUCCESS, $result['status']);
-        $this->assertEquals(200, $result['http_code']);
-        $this->assertEquals(200, $result['response']->getStatus());
-        $this->assertEquals(['Header1' => ['Val1']], $result['response']->getHeaders());
-        $this->assertEquals('Foo', $result['response']->getBodyAsString());
+        self::assertEquals(Client::STATUS_SUCCESS, $result['status']);
+        self::assertEquals(200, $result['http_code']);
+        self::assertEquals(200, $result['response']->getStatus());
+        self::assertEquals(['Header1' => ['Val1']], $result['response']->getHeaders());
+        self::assertEquals('Foo', $result['response']->getBodyAsString());
     }
 
     public function testParseCurlResultEmptyBody(): void
@@ -437,11 +437,11 @@ public function testParseCurlResultEmptyBody(): void
         /** @phpstan-ignore-next-line */
         $result = $client->parseCurlResult($body, 'foobar');
 
-        $this->assertEquals(Client::STATUS_SUCCESS, $result['status']);
-        $this->assertEquals(200, $result['http_code']);
-        $this->assertEquals(200, $result['response']->getStatus());
-        $this->assertEquals(['Header1' => ['Val1']], $result['response']->getHeaders());
-        $this->assertEquals('', $result['response']->getBodyAsString());
+        self::assertEquals(Client::STATUS_SUCCESS, $result['status']);
+        self::assertEquals(200, $result['http_code']);
+        self::assertEquals(200, $result['response']->getStatus());
+        self::assertEquals(['Header1' => ['Val1']], $result['response']->getHeaders());
+        self::assertEquals('', $result['response']->getBodyAsString());
     }
 
     public function testParseCurlError(): void
@@ -459,9 +459,9 @@ public function testParseCurlError(): void
         /** @phpstan-ignore-next-line */
         $result = $client->parseCurlResult($body, 'foobar');
 
-        $this->assertEquals(Client::STATUS_CURLERROR, $result['status']);
-        $this->assertEquals(1, $result['curl_errno']);
-        $this->assertEquals('Curl error', $result['curl_errmsg']);
+        self::assertEquals(Client::STATUS_CURLERROR, $result['status']);
+        self::assertEquals(1, $result['curl_errno']);
+        self::assertEquals('Curl error', $result['curl_errmsg']);
     }
 
     public function testDoRequest(): void
@@ -482,9 +482,9 @@ public function testDoRequest(): void
             ];
         });
         $response = $client->doRequest($request);
-        $this->assertEquals(200, $response->getStatus());
-        $this->assertEquals(['Header1' => ['Val1']], $response->getHeaders());
-        $this->assertEquals('Foo', $response->getBodyAsString());
+        self::assertEquals(200, $response->getStatus());
+        self::assertEquals(['Header1' => ['Val1']], $response->getHeaders());
+        self::assertEquals('Foo', $response->getBodyAsString());
     }
 
     public function testDoRequestCurlError(): void
@@ -506,8 +506,8 @@ public function testDoRequestCurlError(): void
             $response = $client->doRequest($request);
             $this->fail('This should have thrown an exception');
         } catch (ClientException $e) {
-            $this->assertEquals(1, $e->getCode());
-            $this->assertEquals('Curl error', $e->getMessage());
+            self::assertEquals(1, $e->getCode());
+            self::assertEquals('Curl error', $e->getMessage());
         }
     }
 }
diff --git a/tests/HTTP/FunctionsTest.php b/tests/HTTP/FunctionsTest.php
index 720209d..506786a 100644
--- a/tests/HTTP/FunctionsTest.php
+++ b/tests/HTTP/FunctionsTest.php
@@ -15,7 +15,7 @@ class FunctionsTest extends \PHPUnit\Framework\TestCase
      */
     public function testGetHeaderValuesOnValues2(array $result, array $values1, array $values2): void
     {
-        $this->assertEquals($result, getHeaderValues($values1, $values2));
+        self::assertEquals($result, getHeaderValues($values1, $values2));
     }
 
     /**
@@ -45,7 +45,7 @@ public function getHeaderValuesDataOnValues2(): array
      */
     public function testGetHeaderValues($input, array $output): void
     {
-        $this->assertEquals(
+        self::assertEquals(
             $output,
             getHeaderValues($input)
         );
@@ -88,7 +88,7 @@ public function getHeaderValuesData(): array
      */
     public function testPrefer($input, array $output): void
     {
-        $this->assertEquals(
+        self::assertEquals(
             $output,
             parsePrefer($input)
         );
@@ -165,11 +165,11 @@ public function testParseHTTPDate(): void
 
         foreach ($times as $time) {
             $result = parseDate($time);
-            $this->assertEquals($expected, $result->format('U'));
+            self::assertEquals($expected, $result->format('U'));
         }
 
         $result = parseDate('Wed Oct  6 10:26:00 2010');
-        $this->assertEquals(1286360760, $result->format('U'));
+        self::assertEquals(1286360760, $result->format('U'));
     }
 
     public function testParseHTTPDateFail(): void
@@ -194,7 +194,7 @@ public function testParseHTTPDateFail(): void
         ];
 
         foreach ($times as $time) {
-            $this->assertFalse(parseDate($time), 'We used the string: '.$time);
+            self::assertFalse(parseDate($time), 'We used the string: '.$time);
         }
     }
 
@@ -212,7 +212,7 @@ public function testToHTTPDate(): void
     {
         $dt = new \DateTime('2011-12-10 12:00:00 +0200');
 
-        $this->assertEquals(
+        self::assertEquals(
             'Sat, 10 Dec 2011 10:00:00 GMT',
             toDate($dt)
         );
diff --git a/tests/HTTP/MessageDecoratorTest.php b/tests/HTTP/MessageDecoratorTest.php
index bc3e73e..6b58df5 100644
--- a/tests/HTTP/MessageDecoratorTest.php
+++ b/tests/HTTP/MessageDecoratorTest.php
@@ -18,12 +18,12 @@ public function setUp(): void
     public function testBody(): void
     {
         $this->outer->setBody('foo');
-        $this->assertEquals('foo', stream_get_contents($this->inner->getBodyAsStream()));
-        $this->assertEquals('foo', stream_get_contents($this->outer->getBodyAsStream()));
-        $this->assertEquals('foo', $this->inner->getBodyAsString());
-        $this->assertEquals('foo', $this->outer->getBodyAsString());
-        $this->assertEquals('foo', $this->inner->getBody());
-        $this->assertEquals('foo', $this->outer->getBody());
+        self::assertEquals('foo', stream_get_contents($this->inner->getBodyAsStream()));
+        self::assertEquals('foo', stream_get_contents($this->outer->getBodyAsStream()));
+        self::assertEquals('foo', $this->inner->getBodyAsString());
+        self::assertEquals('foo', $this->outer->getBodyAsString());
+        self::assertEquals('foo', $this->inner->getBody());
+        self::assertEquals('foo', $this->outer->getBody());
     }
 
     public function testHeaders(): void
@@ -32,60 +32,60 @@ public function testHeaders(): void
             'a' => 'b',
         ]);
 
-        $this->assertEquals(['a' => ['b']], $this->inner->getHeaders());
-        $this->assertEquals(['a' => ['b']], $this->outer->getHeaders());
+        self::assertEquals(['a' => ['b']], $this->inner->getHeaders());
+        self::assertEquals(['a' => ['b']], $this->outer->getHeaders());
 
         $this->outer->setHeaders([
             'c' => 'd',
         ]);
 
-        $this->assertEquals(['a' => ['b'], 'c' => ['d']], $this->inner->getHeaders());
-        $this->assertEquals(['a' => ['b'], 'c' => ['d']], $this->outer->getHeaders());
+        self::assertEquals(['a' => ['b'], 'c' => ['d']], $this->inner->getHeaders());
+        self::assertEquals(['a' => ['b'], 'c' => ['d']], $this->outer->getHeaders());
 
         $this->outer->addHeaders([
             'e' => 'f',
         ]);
 
-        $this->assertEquals(['a' => ['b'], 'c' => ['d'], 'e' => ['f']], $this->inner->getHeaders());
-        $this->assertEquals(['a' => ['b'], 'c' => ['d'], 'e' => ['f']], $this->outer->getHeaders());
+        self::assertEquals(['a' => ['b'], 'c' => ['d'], 'e' => ['f']], $this->inner->getHeaders());
+        self::assertEquals(['a' => ['b'], 'c' => ['d'], 'e' => ['f']], $this->outer->getHeaders());
     }
 
     public function testHeader(): void
     {
-        $this->assertFalse($this->outer->hasHeader('a'));
-        $this->assertFalse($this->inner->hasHeader('a'));
+        self::assertFalse($this->outer->hasHeader('a'));
+        self::assertFalse($this->inner->hasHeader('a'));
         $this->outer->setHeader('a', 'c');
-        $this->assertTrue($this->outer->hasHeader('a'));
-        $this->assertTrue($this->inner->hasHeader('a'));
+        self::assertTrue($this->outer->hasHeader('a'));
+        self::assertTrue($this->inner->hasHeader('a'));
 
-        $this->assertEquals('c', $this->inner->getHeader('A'));
-        $this->assertEquals('c', $this->outer->getHeader('A'));
+        self::assertEquals('c', $this->inner->getHeader('A'));
+        self::assertEquals('c', $this->outer->getHeader('A'));
 
         $this->outer->addHeader('A', 'd');
 
-        $this->assertEquals(
+        self::assertEquals(
             ['c', 'd'],
             $this->inner->getHeaderAsArray('A')
         );
-        $this->assertEquals(
+        self::assertEquals(
             ['c', 'd'],
             $this->outer->getHeaderAsArray('A')
         );
 
         $success = $this->outer->removeHeader('a');
 
-        $this->assertTrue($success);
-        $this->assertNull($this->inner->getHeader('A'));
-        $this->assertNull($this->outer->getHeader('A'));
+        self::assertTrue($success);
+        self::assertNull($this->inner->getHeader('A'));
+        self::assertNull($this->outer->getHeader('A'));
 
-        $this->assertFalse($this->outer->removeHeader('i-dont-exist'));
+        self::assertFalse($this->outer->removeHeader('i-dont-exist'));
     }
 
     public function testHttpVersion(): void
     {
         $this->outer->setHttpVersion('1.0');
 
-        $this->assertEquals('1.0', $this->inner->getHttpVersion());
-        $this->assertEquals('1.0', $this->outer->getHttpVersion());
+        self::assertEquals('1.0', $this->inner->getHttpVersion());
+        self::assertEquals('1.0', $this->outer->getHttpVersion());
     }
 }
diff --git a/tests/HTTP/MessageTest.php b/tests/HTTP/MessageTest.php
index 579b9dc..07d6ab0 100644
--- a/tests/HTTP/MessageTest.php
+++ b/tests/HTTP/MessageTest.php
@@ -9,7 +9,7 @@ class MessageTest extends \PHPUnit\Framework\TestCase
     public function testConstruct(): void
     {
         $message = new MessageMock();
-        $this->assertInstanceOf('Sabre\HTTP\Message', $message);
+        self::assertInstanceOf('Sabre\HTTP\Message', $message);
     }
 
     public function testStreamBody(): void
@@ -22,11 +22,11 @@ public function testStreamBody(): void
         $message = new MessageMock();
         $message->setBody($h);
 
-        $this->assertEquals($body, $message->getBodyAsString());
+        self::assertEquals($body, $message->getBodyAsString());
         rewind($h);
-        $this->assertEquals($body, stream_get_contents($message->getBodyAsStream()));
+        self::assertEquals($body, stream_get_contents($message->getBodyAsStream()));
         rewind($h);
-        $this->assertEquals($body, stream_get_contents($message->getBody()));
+        self::assertEquals($body, stream_get_contents($message->getBody()));
     }
 
     public function testStringBody(): void
@@ -36,9 +36,9 @@ public function testStringBody(): void
         $message = new MessageMock();
         $message->setBody($body);
 
-        $this->assertEquals($body, $message->getBodyAsString());
-        $this->assertEquals($body, stream_get_contents($message->getBodyAsStream()));
-        $this->assertEquals($body, $message->getBody());
+        self::assertEquals($body, $message->getBodyAsString());
+        self::assertEquals($body, stream_get_contents($message->getBodyAsStream()));
+        self::assertEquals($body, $message->getBody());
     }
 
     public function testCallbackBodyAsString(): void
@@ -50,7 +50,7 @@ public function testCallbackBodyAsString(): void
 
         $string = $message->getBodyAsString();
 
-        $this->assertSame('foo', $string);
+        self::assertSame('foo', $string);
     }
 
     public function testCallbackBodyAsStream(): void
@@ -62,7 +62,7 @@ public function testCallbackBodyAsStream(): void
 
         $stream = $message->getBodyAsStream();
 
-        $this->assertSame('foo', stream_get_contents($stream));
+        self::assertSame('foo', stream_get_contents($stream));
     }
 
     public function testGetBodyWhenCallback(): void
@@ -72,7 +72,7 @@ public function testGetBodyWhenCallback(): void
         $message = new MessageMock();
         $message->setBody($callback);
 
-        $this->assertSame($callback, $message->getBody());
+        self::assertSame($callback, $message->getBody());
     }
 
     /**
@@ -96,7 +96,7 @@ public function testLongStreamToStringBody(): void
         $message->setBody($body);
         $message->setHeader('Content-Length', '4');
 
-        $this->assertEquals(
+        self::assertEquals(
             'cdef',
             $message->getBodyAsString()
         );
@@ -116,7 +116,7 @@ public function testEmptyContentLengthHeader(): void
         $message->setBody($body);
         $message->setHeader('Content-Length', '');
 
-        $this->assertEquals(
+        self::assertEquals(
             'cdefg',
             $message->getBodyAsString()
         );
@@ -127,7 +127,7 @@ public function testGetEmptyBodyStream(): void
         $message = new MessageMock();
         $body = $message->getBodyAsStream();
 
-        $this->assertEquals('', stream_get_contents($body));
+        self::assertEquals('', stream_get_contents($body));
     }
 
     public function testGetEmptyBodyString(): void
@@ -135,7 +135,7 @@ public function testGetEmptyBodyString(): void
         $message = new MessageMock();
         $body = $message->getBodyAsString();
 
-        $this->assertEquals('', $body);
+        self::assertEquals('', $body);
     }
 
     public function testHeaders(): void
@@ -144,14 +144,14 @@ public function testHeaders(): void
         $message->setHeader('X-Foo', 'bar');
 
         // Testing caselessness
-        $this->assertEquals('bar', $message->getHeader('X-Foo'));
-        $this->assertEquals('bar', $message->getHeader('x-fOO'));
+        self::assertEquals('bar', $message->getHeader('X-Foo'));
+        self::assertEquals('bar', $message->getHeader('x-fOO'));
 
-        $this->assertTrue(
+        self::assertTrue(
             $message->removeHeader('X-FOO')
         );
-        $this->assertNull($message->getHeader('X-Foo'));
-        $this->assertFalse(
+        self::assertNull($message->getHeader('X-Foo'));
+        self::assertFalse(
             $message->removeHeader('X-FOO')
         );
     }
@@ -166,7 +166,7 @@ public function testSetHeaders(): void
         ];
 
         $message->setHeaders($headers);
-        $this->assertEquals($headers, $message->getHeaders());
+        self::assertEquals($headers, $message->getHeaders());
 
         $message->setHeaders([
             'X-Foo' => ['3', '4'],
@@ -178,7 +178,7 @@ public function testSetHeaders(): void
             'X-Bar' => ['5'],
         ];
 
-        $this->assertEquals($expected, $message->getHeaders());
+        self::assertEquals($expected, $message->getHeaders());
     }
 
     public function testAddHeaders(): void
@@ -191,7 +191,7 @@ public function testAddHeaders(): void
         ];
 
         $message->addHeaders($headers);
-        $this->assertEquals($headers, $message->getHeaders());
+        self::assertEquals($headers, $message->getHeaders());
 
         $message->addHeaders([
             'X-Foo' => ['3', '4'],
@@ -203,7 +203,7 @@ public function testAddHeaders(): void
             'X-Bar' => ['2', '5'],
         ];
 
-        $this->assertEquals($expected, $message->getHeaders());
+        self::assertEquals($expected, $message->getHeaders());
     }
 
     public function testSendBody(): void
@@ -222,7 +222,7 @@ public function testSendBody(): void
         $body = $message->getBody();
         rewind($body);
 
-        $this->assertEquals('bar', stream_get_contents($body));
+        self::assertEquals('bar', stream_get_contents($body));
     }
 
     public function testMultipleHeaders(): void
@@ -231,24 +231,24 @@ public function testMultipleHeaders(): void
         $message->setHeader('a', '1');
         $message->addHeader('A', '2');
 
-        $this->assertEquals(
+        self::assertEquals(
             '1,2',
             $message->getHeader('A')
         );
-        $this->assertEquals(
+        self::assertEquals(
             '1,2',
             $message->getHeader('a')
         );
 
-        $this->assertEquals(
+        self::assertEquals(
             ['1', '2'],
             $message->getHeaderAsArray('a')
         );
-        $this->assertEquals(
+        self::assertEquals(
             ['1', '2'],
             $message->getHeaderAsArray('A')
         );
-        $this->assertEquals(
+        self::assertEquals(
             [],
             $message->getHeaderAsArray('B')
         );
@@ -258,9 +258,9 @@ public function testHasHeaders(): void
     {
         $message = new MessageMock();
 
-        $this->assertFalse($message->hasHeader('X-Foo'));
+        self::assertFalse($message->hasHeader('X-Foo'));
         $message->setHeader('X-Foo', 'Bar');
-        $this->assertTrue($message->hasHeader('X-Foo'));
+        self::assertTrue($message->hasHeader('X-Foo'));
     }
 
     /**
diff --git a/tests/HTTP/NegotiateTest.php b/tests/HTTP/NegotiateTest.php
index 40738e0..4ee2002 100644
--- a/tests/HTTP/NegotiateTest.php
+++ b/tests/HTTP/NegotiateTest.php
@@ -13,7 +13,7 @@ class NegotiateTest extends \PHPUnit\Framework\TestCase
      */
     public function testNegotiate(?string $acceptHeader, array $available, ?string $expected): void
     {
-        $this->assertEquals(
+        self::assertEquals(
             $expected,
             negotiateContentType($acceptHeader, $available)
         );
diff --git a/tests/HTTP/RequestDecoratorTest.php b/tests/HTTP/RequestDecoratorTest.php
index d768135..a6f661a 100644
--- a/tests/HTTP/RequestDecoratorTest.php
+++ b/tests/HTTP/RequestDecoratorTest.php
@@ -18,37 +18,37 @@ public function setUp(): void
     public function testMethod(): void
     {
         $this->outer->setMethod('FOO');
-        $this->assertEquals('FOO', $this->inner->getMethod());
-        $this->assertEquals('FOO', $this->outer->getMethod());
+        self::assertEquals('FOO', $this->inner->getMethod());
+        self::assertEquals('FOO', $this->outer->getMethod());
     }
 
     public function testUrl(): void
     {
         $this->outer->setUrl('/foo');
-        $this->assertEquals('/foo', $this->inner->getUrl());
-        $this->assertEquals('/foo', $this->outer->getUrl());
+        self::assertEquals('/foo', $this->inner->getUrl());
+        self::assertEquals('/foo', $this->outer->getUrl());
     }
 
     public function testAbsoluteUrl(): void
     {
         $this->outer->setAbsoluteUrl('http://example.org/foo');
-        $this->assertEquals('http://example.org/foo', $this->inner->getAbsoluteUrl());
-        $this->assertEquals('http://example.org/foo', $this->outer->getAbsoluteUrl());
+        self::assertEquals('http://example.org/foo', $this->inner->getAbsoluteUrl());
+        self::assertEquals('http://example.org/foo', $this->outer->getAbsoluteUrl());
     }
 
     public function testBaseUrl(): void
     {
         $this->outer->setBaseUrl('/foo');
-        $this->assertEquals('/foo', $this->inner->getBaseUrl());
-        $this->assertEquals('/foo', $this->outer->getBaseUrl());
+        self::assertEquals('/foo', $this->inner->getBaseUrl());
+        self::assertEquals('/foo', $this->outer->getBaseUrl());
     }
 
     public function testPath(): void
     {
         $this->outer->setBaseUrl('/foo');
         $this->outer->setUrl('/foo/bar');
-        $this->assertEquals('bar', $this->inner->getPath());
-        $this->assertEquals('bar', $this->outer->getPath());
+        self::assertEquals('bar', $this->inner->getPath());
+        self::assertEquals('bar', $this->outer->getPath());
     }
 
     public function testQueryParams(): void
@@ -60,8 +60,8 @@ public function testQueryParams(): void
             'e' => null,
         ];
 
-        $this->assertEquals($expected, $this->inner->getQueryParameters());
-        $this->assertEquals($expected, $this->outer->getQueryParameters());
+        self::assertEquals($expected, $this->inner->getQueryParameters());
+        self::assertEquals($expected, $this->outer->getQueryParameters());
     }
 
     public function testPostData(): void
@@ -73,8 +73,8 @@ public function testPostData(): void
         ];
 
         $this->outer->setPostData($postData);
-        $this->assertEquals($postData, $this->inner->getPostData());
-        $this->assertEquals($postData, $this->outer->getPostData());
+        self::assertEquals($postData, $this->inner->getPostData());
+        self::assertEquals($postData, $this->outer->getPostData());
     }
 
     public function testServerData(): void
@@ -84,11 +84,11 @@ public function testServerData(): void
         ];
 
         $this->outer->setRawServerData($serverData);
-        $this->assertEquals('On', $this->inner->getRawServerValue('HTTPS'));
-        $this->assertEquals('On', $this->outer->getRawServerValue('HTTPS'));
+        self::assertEquals('On', $this->inner->getRawServerValue('HTTPS'));
+        self::assertEquals('On', $this->outer->getRawServerValue('HTTPS'));
 
-        $this->assertNull($this->inner->getRawServerValue('FOO'));
-        $this->assertNull($this->outer->getRawServerValue('FOO'));
+        self::assertNull($this->inner->getRawServerValue('FOO'));
+        self::assertNull($this->outer->getRawServerValue('FOO'));
     }
 
     public function testToString(): void
@@ -98,6 +98,6 @@ public function testToString(): void
         $this->inner->setBody('foo');
         $this->inner->setHeader('foo', 'bar');
 
-        $this->assertEquals((string) $this->inner, (string) $this->outer);
+        self::assertEquals((string) $this->inner, (string) $this->outer);
     }
 }
diff --git a/tests/HTTP/RequestTest.php b/tests/HTTP/RequestTest.php
index d1a8644..2e154b4 100644
--- a/tests/HTTP/RequestTest.php
+++ b/tests/HTTP/RequestTest.php
@@ -11,9 +11,9 @@ public function testConstruct(): void
         $request = new Request('GET', '/foo', [
             'User-Agent' => 'Evert',
         ]);
-        $this->assertEquals('GET', $request->getMethod());
-        $this->assertEquals('/foo', $request->getUrl());
-        $this->assertEquals([
+        self::assertEquals('GET', $request->getMethod());
+        self::assertEquals('/foo', $request->getUrl());
+        self::assertEquals([
             'User-Agent' => ['Evert'],
         ], $request->getHeaders());
     }
@@ -21,7 +21,7 @@ public function testConstruct(): void
     public function testGetQueryParameters(): void
     {
         $request = new Request('GET', '/foo?a=b&c&d=e');
-        $this->assertEquals([
+        self::assertEquals([
             'a' => 'b',
             'c' => null,
             'd' => 'e',
@@ -31,7 +31,7 @@ public function testGetQueryParameters(): void
     public function testGetQueryParametersNoData(): void
     {
         $request = new Request('GET', '/foo');
-        $this->assertEquals([], $request->getQueryParameters());
+        self::assertEquals([], $request->getQueryParameters());
     }
 
     /**
@@ -43,7 +43,7 @@ public function testCreateFromPHPRequest(): void
         $_SERVER['REQUEST_METHOD'] = 'PUT';
 
         $request = Sapi::getRequest();
-        $this->assertEquals('PUT', $request->getMethod());
+        self::assertEquals('PUT', $request->getMethod());
     }
 
     public function testGetAbsoluteUrl(): void
@@ -52,7 +52,7 @@ public function testGetAbsoluteUrl(): void
             'Host' => 'sabredav.org',
         ]);
 
-        $this->assertEquals('http://sabredav.org/foo', $r->getAbsoluteUrl());
+        self::assertEquals('http://sabredav.org/foo', $r->getAbsoluteUrl());
 
         $s = [
             'HTTP_HOST' => 'sabredav.org',
@@ -63,7 +63,7 @@ public function testGetAbsoluteUrl(): void
 
         $r = Sapi::createFromServerArray($s);
 
-        $this->assertEquals('https://sabredav.org/foo', $r->getAbsoluteUrl());
+        self::assertEquals('https://sabredav.org/foo', $r->getAbsoluteUrl());
     }
 
     public function testGetPostData(): void
@@ -73,7 +73,7 @@ public function testGetPostData(): void
         ];
         $r = new Request('POST', '/');
         $r->setPostData($post);
-        $this->assertEquals($post, $r->getPostData());
+        self::assertEquals($post, $r->getPostData());
     }
 
     public function testGetPath(): void
@@ -82,7 +82,7 @@ public function testGetPath(): void
         $request->setBaseUrl('/foo');
         $request->setUrl('/foo/bar/');
 
-        $this->assertEquals('bar', $request->getPath());
+        self::assertEquals('bar', $request->getPath());
     }
 
     public function testGetPathStrippedQuery(): void
@@ -90,7 +90,7 @@ public function testGetPathStrippedQuery(): void
         $request = new Request('GET', '/foo/bar?a=B');
         $request->setBaseUrl('/foo');
 
-        $this->assertEquals('bar', $request->getPath());
+        self::assertEquals('bar', $request->getPath());
     }
 
     public function testGetPathMissingSlash(): void
@@ -98,7 +98,7 @@ public function testGetPathMissingSlash(): void
         $request = new Request('GET', '/foo');
         $request->setBaseUrl('/foo/');
 
-        $this->assertEquals('', $request->getPath());
+        self::assertEquals('', $request->getPath());
     }
 
     public function testGetPathOutsideBaseUrl(): void
@@ -119,7 +119,7 @@ public function testToString(): void
                   ."Content-Type: text/xml\r\n"
                   ."\r\n"
                   .'foo';
-        $this->assertEquals($expected, (string) $request);
+        self::assertEquals($expected, (string) $request);
     }
 
     public function testToStringAuthorization(): void
@@ -132,7 +132,7 @@ public function testToStringAuthorization(): void
                   ."Authorization: Basic REDACTED\r\n"
                   ."\r\n"
                   .'foo';
-        $this->assertEquals($expected, (string) $request);
+        self::assertEquals($expected, (string) $request);
     }
 
     public function testAbsoluteUrlHttp(): void
diff --git a/tests/HTTP/ResponseDecoratorTest.php b/tests/HTTP/ResponseDecoratorTest.php
index 83f89d8..1d16da1 100644
--- a/tests/HTTP/ResponseDecoratorTest.php
+++ b/tests/HTTP/ResponseDecoratorTest.php
@@ -18,10 +18,10 @@ public function setUp(): void
     public function testStatus(): void
     {
         $this->outer->setStatus(201);
-        $this->assertEquals(201, $this->inner->getStatus());
-        $this->assertEquals(201, $this->outer->getStatus());
-        $this->assertEquals('Created', $this->inner->getStatusText());
-        $this->assertEquals('Created', $this->outer->getStatusText());
+        self::assertEquals(201, $this->inner->getStatus());
+        self::assertEquals(201, $this->outer->getStatus());
+        self::assertEquals('Created', $this->inner->getStatusText());
+        self::assertEquals('Created', $this->outer->getStatusText());
     }
 
     public function testToString(): void
@@ -30,6 +30,6 @@ public function testToString(): void
         $this->inner->setBody('foo');
         $this->inner->setHeader('foo', 'bar');
 
-        $this->assertEquals((string) $this->inner, (string) $this->outer);
+        self::assertEquals((string) $this->inner, (string) $this->outer);
     }
 }
diff --git a/tests/HTTP/ResponseTest.php b/tests/HTTP/ResponseTest.php
index 52680cd..042b7e9 100644
--- a/tests/HTTP/ResponseTest.php
+++ b/tests/HTTP/ResponseTest.php
@@ -9,24 +9,24 @@ class ResponseTest extends \PHPUnit\Framework\TestCase
     public function testConstruct(): void
     {
         $response = new Response(200, ['Content-Type' => 'text/xml']);
-        $this->assertEquals(200, $response->getStatus());
-        $this->assertEquals('OK', $response->getStatusText());
+        self::assertEquals(200, $response->getStatus());
+        self::assertEquals('OK', $response->getStatusText());
     }
 
     public function testSetStatus(): void
     {
         $response = new Response();
         $response->setStatus('402 Where\'s my money?');
-        $this->assertEquals(402, $response->getStatus());
-        $this->assertEquals('Where\'s my money?', $response->getStatusText());
+        self::assertEquals(402, $response->getStatus());
+        self::assertEquals('Where\'s my money?', $response->getStatusText());
     }
 
     public function testSetStatusWithoutText(): void
     {
         $response = new Response();
         $response->setStatus('402');
-        $this->assertEquals(402, $response->getStatus());
-        $this->assertEquals('Payment Required', $response->getStatusText());
+        self::assertEquals(402, $response->getStatus());
+        self::assertEquals('Payment Required', $response->getStatusText());
     }
 
     public function testInvalidStatus(): void
@@ -44,6 +44,6 @@ public function testToString(): void
                   ."Content-Type: text/xml\r\n"
                   ."\r\n"
                   .'foo';
-        $this->assertEquals($expected, (string) $response);
+        self::assertEquals($expected, (string) $response);
     }
 }
diff --git a/tests/HTTP/SapiTest.php b/tests/HTTP/SapiTest.php
index 39d97ed..1deb941 100644
--- a/tests/HTTP/SapiTest.php
+++ b/tests/HTTP/SapiTest.php
@@ -17,18 +17,18 @@ public function testConstructFromServerArray(): void
             'SERVER_PROTOCOL' => 'HTTP/1.0',
         ]);
 
-        $this->assertEquals('GET', $request->getMethod());
-        $this->assertEquals('/foo', $request->getUrl());
-        $this->assertEquals([
+        self::assertEquals('GET', $request->getMethod());
+        self::assertEquals('/foo', $request->getUrl());
+        self::assertEquals([
             'User-Agent' => ['Evert'],
             'Content-Type' => ['text/xml'],
             'Content-Length' => ['400'],
         ], $request->getHeaders());
 
-        $this->assertEquals('1.0', $request->getHttpVersion());
+        self::assertEquals('1.0', $request->getHttpVersion());
 
-        $this->assertEquals('400', $request->getRawServerValue('CONTENT_LENGTH'));
-        $this->assertNull($request->getRawServerValue('FOO'));
+        self::assertEquals('400', $request->getRawServerValue('CONTENT_LENGTH'));
+        self::assertNull($request->getRawServerValue('FOO'));
     }
 
     public function testConstructFromServerArrayOnNullUrl(): void
@@ -68,9 +68,9 @@ public function testConstructPHPAuth(): void
             'PHP_AUTH_PW' => 'pass',
         ]);
 
-        $this->assertEquals('GET', $request->getMethod());
-        $this->assertEquals('/foo', $request->getUrl());
-        $this->assertEquals([
+        self::assertEquals('GET', $request->getMethod());
+        self::assertEquals('/foo', $request->getUrl());
+        self::assertEquals([
             'Authorization' => ['Basic '.base64_encode('user:pass')],
         ], $request->getHeaders());
     }
@@ -83,9 +83,9 @@ public function testConstructPHPAuthDigest(): void
             'PHP_AUTH_DIGEST' => 'blabla',
         ]);
 
-        $this->assertEquals('GET', $request->getMethod());
-        $this->assertEquals('/foo', $request->getUrl());
-        $this->assertEquals([
+        self::assertEquals('GET', $request->getMethod());
+        self::assertEquals('/foo', $request->getUrl());
+        self::assertEquals([
             'Authorization' => ['Digest blabla'],
         ], $request->getHeaders());
     }
@@ -98,9 +98,9 @@ public function testConstructRedirectAuth(): void
             'REDIRECT_HTTP_AUTHORIZATION' => 'Basic bla',
         ]);
 
-        $this->assertEquals('GET', $request->getMethod());
-        $this->assertEquals('/foo', $request->getUrl());
-        $this->assertEquals([
+        self::assertEquals('GET', $request->getMethod());
+        self::assertEquals('/foo', $request->getUrl());
+        self::assertEquals([
             'Authorization' => ['Basic bla'],
         ], $request->getHeaders());
     }
@@ -131,7 +131,7 @@ public function testSend(): void
         $result = ob_get_clean();
         header_remove();
 
-        $this->assertEquals(
+        self::assertEquals(
             [
                 'Content-Type: text/xml;charset=UTF-8',
                 'Content-Type: application/xml',
@@ -139,7 +139,7 @@ public function testSend(): void
             $headers
         );
 
-        $this->assertEquals('foo', $result);
+        self::assertEquals('foo', $result);
     }
 
     /**
@@ -161,7 +161,7 @@ public function testSendLimitedByContentLengthString(): void
         $result = ob_get_clean();
         header_remove();
 
-        $this->assertEquals('Send this sentence.', $result);
+        self::assertEquals('Send this sentence.', $result);
     }
 
     /**
@@ -175,7 +175,7 @@ public function testRecognizeHttp2(): void
             'REQUEST_METHOD' => 'GET',
         ]);
 
-        $this->assertEquals('2.0', $request->getHttpVersion());
+        self::assertEquals('2.0', $request->getHttpVersion());
     }
 
     /**
@@ -200,7 +200,7 @@ public function testSendLimitedByContentLengthStream(): void
         $result = ob_get_clean();
         header_remove();
 
-        $this->assertEquals('Send this sentence.', $result);
+        self::assertEquals('Send this sentence.', $result);
     }
 
     /**
@@ -246,7 +246,7 @@ public function testSendContentRangeStream(
         $result = ob_get_clean();
         header_remove();
 
-        $this->assertEquals($partial, $result);
+        self::assertEquals($partial, $result);
     }
 
     /**
@@ -298,7 +298,7 @@ public function testSendWorksWithCallbackAsBody(): void
 
         $result = ob_get_clean();
 
-        $this->assertEquals('foo', $result);
+        self::assertEquals('foo', $result);
     }
 
     public function testSendConnectionAborted(): void
diff --git a/tests/HTTP/URLUtilTest.php b/tests/HTTP/URLUtilTest.php
index 7ce73c3..94f2118 100644
--- a/tests/HTTP/URLUtilTest.php
+++ b/tests/HTTP/URLUtilTest.php
@@ -15,7 +15,7 @@ public function testEncodePath(): void
 
         $newStr = encodePath($str);
 
-        $this->assertEquals(
+        self::assertEquals(
             '%00%01%02%03%04%05%06%07%08%09%0a%0b%0c%0d%0e%0f'.
             '%10%11%12%13%14%15%16%17%18%19%1a%1b%1c%1d%1e%1f'.
             '%20%21%22%23%24%25%26%27()%2a%2b%2c-./'.
@@ -26,7 +26,7 @@ public function testEncodePath(): void
             'pqrstuvwxyz%7b%7c%7d~%7f',
             $newStr);
 
-        $this->assertEquals($str, decodePath($newStr));
+        self::assertEquals($str, decodePath($newStr));
     }
 
     public function testEncodePathSegment(): void
@@ -38,9 +38,9 @@ public function testEncodePathSegment(): void
 
         $newStr = encodePathSegment($str);
 
-        // Note: almost exactly the same as the last test, with the
-        // exception of the encoding of / (ascii code 2f)
-        $this->assertEquals(
+        // Note: almost exactly the same as the last test, except for
+        // the encoding of / (ascii code 2f)
+        self::assertEquals(
             '%00%01%02%03%04%05%06%07%08%09%0a%0b%0c%0d%0e%0f'.
             '%10%11%12%13%14%15%16%17%18%19%1a%1b%1c%1d%1e%1f'.
             '%20%21%22%23%24%25%26%27()%2a%2b%2c-.%2f'.
@@ -51,14 +51,14 @@ public function testEncodePathSegment(): void
             'pqrstuvwxyz%7b%7c%7d~%7f',
             $newStr);
 
-        $this->assertEquals($str, decodePathSegment($newStr));
+        self::assertEquals($str, decodePathSegment($newStr));
     }
 
     public function testDecode(): void
     {
         $str = 'Hello%20Test+Test2.txt';
         $newStr = decodePath($str);
-        $this->assertEquals('Hello Test+Test2.txt', $newStr);
+        self::assertEquals('Hello Test+Test2.txt', $newStr);
     }
 
     /**
@@ -68,7 +68,7 @@ public function testDecodeUmlaut(): void
     {
         $str = 'Hello%C3%BC.txt';
         $newStr = decodePath($str);
-        $this->assertEquals("Hello\xC3\xBC.txt", $newStr);
+        self::assertEquals("Hello\xC3\xBC.txt", $newStr);
     }
 
     /**
@@ -86,7 +86,7 @@ public function testDecodeSlavicWords(): void
         foreach ($words as $word) {
             $str = rawurlencode($word);
             $newStr = decodePath($str);
-            $this->assertEquals($word, $newStr);
+            self::assertEquals($word, $newStr);
         }
     }
 
@@ -97,7 +97,7 @@ public function testDecodeUmlautLatin1(): void
     {
         $str = 'Hello%FC.txt';
         $newStr = decodePath($str);
-        $this->assertEquals("Hello\xC3\xBC.txt", $newStr);
+        self::assertEquals("Hello\xC3\xBC.txt", $newStr);
     }
 
     /**
@@ -109,6 +109,6 @@ public function testDecodeAccentsWindows7(): void
     {
         $str = '/webdav/%C3%A0fo%C3%B3';
         $newStr = decodePath($str);
-        $this->assertEquals(strtolower($str), encodePath($newStr));
+        self::assertEquals(strtolower($str), encodePath($newStr));
     }
 }