Allow both upper and lower case in unicode escape.

Issue #1

pom.xml

@@ -5,7 +5,7 @@
 
     <groupId>org.leadpony</groupId>
     <artifactId>jsonp-test-suite</artifactId>
-    <version>1.3.0</version>
+    <version>1.4.0-SNAPSHOT</version>
     <packaging>jar</packaging>
 
     <name>JSON-P Test Suite</name>

src/main/java/org/leadpony/jsonp/testsuite/helper/JsonAssertions.java

@@ -0,0 +1,87 @@
+/*
+ * Copyright 2019 the JSON-P Test Suite Authors.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package org.leadpony.jsonp.testsuite.helper;
+
+import org.assertj.core.api.AbstractAssert;
+
+/**
+ * @author leadpony
+ */
+public final class JsonAssertions {
+
+    public static JsonAssertion assertThat(String actual) {
+        return new JsonAssertion(actual);
+    }
+
+    private JsonAssertions() {
+    }
+
+    /**
+     * @author leadpony
+     */
+    public static final class JsonAssertion extends AbstractAssert<JsonAssertion, String> {
+
+        private JsonAssertion(String actual) {
+            super(actual, JsonAssertion.class);
+        }
+
+        public JsonAssertion isEqualTo(String expected) {
+            isNotNull();
+            if (!normalizeJson(actual).equals(normalizeJson(expected))) {
+                failWithMessage("Expected JSON to be <%s> but was <%s>", expected, actual);
+            }
+            return this;
+        }
+
+        private static String normalizeJson(String json) {
+            StringBuilder builder = new StringBuilder();
+            final int length = json.length();
+            for (int i = 0; i < length; i++) {
+                char c = json.charAt(i);
+                builder.append(c);
+                if (c == '\"') {
+                    while (++i < length) {
+                        c = json.charAt(i);
+                        builder.append(c);
+                        if (c == '\"') {
+                            break;
+                        } else if (c == '\\') {
+                            if (++i < length) {
+                                c = json.charAt(i);
+                                builder.append(c);
+                                if (c == 'u') {
+                                    int j = 0;
+                                    while (j++ < 4 && ++i < length) {
+                                        c = json.charAt(i);
+                                        builder.append(toUpperHexDigit(c));
+                                    }
+                                }
+                            }
+                        }
+                    }
+                }
+            }
+            return builder.toString();
+        }
+
+        private static char toUpperHexDigit(char c) {
+            if ('a' <= c && c <= 'f') {
+                return (char) ('A' + (c - 'a'));
+            }
+            return c;
+        }
+    }
+}

src/main/java/org/leadpony/jsonp/testsuite/tests/JsonGeneratorTest.java

@@ -28,6 +28,7 @@
 import org.junit.jupiter.api.Test;
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.EnumSource;
+import org.leadpony.jsonp.testsuite.helper.JsonAssertions;
 
 /**
  * A test type to test {@link JsonGenerator}.
@@ -272,7 +273,7 @@ public void writeShouldWriteJsonValue(JsonValueTestCase test) {
             g.write(test.getJsonValue());
         });
 
-        assertThat(actual).isEqualTo(test.getString());
+        JsonAssertions.assertThat(actual).isEqualTo(test.getString());
     }
 
     /**

src/main/java/org/leadpony/jsonp/testsuite/tests/JsonStringTest.java

@@ -15,14 +15,13 @@
  */
 package org.leadpony.jsonp.testsuite.tests;
 
-import static org.assertj.core.api.Assertions.assertThat;
-
 import java.util.stream.Stream;
 
 import javax.json.JsonString;
 
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.leadpony.jsonp.testsuite.helper.JsonAssertions;
 
 /**
  * A test type to test {@link JsonString}.
@@ -42,6 +41,6 @@ public void toStringShouldEscapeString(JsonValueTestCase test) {
 
         String actual = sut.toString();
 
-        assertThat(actual).isEqualTo(test.getString());
+        JsonAssertions.assertThat(actual).isEqualTo(test.getString());
     }
 }

src/main/java/org/leadpony/jsonp/testsuite/tests/JsonWriterTest.java

@@ -34,6 +34,7 @@
 import org.junit.jupiter.params.ParameterizedTest;
 import org.junit.jupiter.params.provider.EnumSource;
 import org.junit.jupiter.params.provider.MethodSource;
+import org.leadpony.jsonp.testsuite.helper.JsonAssertions;
 
 /**
  * A test type to test {@link JsonWriter}.
@@ -57,7 +58,7 @@ public void writeShouldWriteJsonValueAsExpected(JsonValueTestCase test) {
             writer.write(test.getJsonValue());
         });
 
-        assertThat(actual).isEqualTo(test.getString());
+        JsonAssertions.assertThat(actual).isEqualTo(test.getString());
     }
 
     @ParameterizedTest