Make hashCode cache tests less brittle.

Author: davidmorgan

test/list/built_list_test.dart

@@ -113,10 +113,13 @@ void main() {
     });
 
     test('caches hash', () {
-      var list = BuiltList<Object>([_HashcodeOnlyOnce()]);
+      var hashCodeSpy = HashCodeSpy();
+      var list = BuiltList<Object>([hashCodeSpy]);
 
+      hashCodeSpy.hashCodeSeen = 0;
       list.hashCode;
       list.hashCode;
+      expect(hashCodeSpy.hashCodeSeen, 1);
     });
 
     test('compares equal to same instance', () {
@@ -452,15 +455,3 @@ void main() {
 class _A {}
 
 class _ExtendsA extends _A {}
-
-class _HashcodeOnlyOnce {
-  bool hashCodeAllowed = true;
-
-  @override
-  // ignore: hash_and_equals
-  int get hashCode {
-    expect(hashCodeAllowed, isTrue);
-    hashCodeAllowed = false;
-    return 0;
-  }
-}

test/list_multimap/built_list_multimap_test.dart

@@ -212,12 +212,15 @@ void main() {
     });
 
     test('caches hash', () {
+      var hashCodeSpy = HashCodeSpy();
       var multimap = BuiltListMultimap<Object, Object>({
-        1: [_HashcodeOnlyOnce()]
+        1: [hashCodeSpy]
       });
 
+      hashCodeSpy.hashCodeSeen = 0;
       multimap.hashCode;
       multimap.hashCode;
+      expect(hashCodeSpy.hashCodeSeen, 1);
     });
 
     test('compares equal to same instance', () {
@@ -600,18 +603,6 @@ class _A {}
 
 class _ExtendsA extends _A {}
 
-class _HashcodeOnlyOnce {
-  bool hashCodeAllowed = true;
-
-  @override
-  // ignore: hash_and_equals
-  int get hashCode {
-    expect(hashCodeAllowed, isTrue);
-    hashCodeAllowed = false;
-    return 0;
-  }
-}
-
 // All the methods from `ListMultimap` that we care about, to avoid taking a
 // dependency on `quiver`.
 class _ListMultimap<K, V> {

test/map/built_map_test.dart

@@ -186,10 +186,13 @@ void main() {
     });
 
     test('caches hash', () {
-      var map = BuiltMap<Object, Object>({1: _HashcodeOnlyOnce()});
+      var hashCodeSpy = HashCodeSpy();
+      var map = BuiltMap<Object, Object>({1: hashCodeSpy});
 
+      hashCodeSpy.hashCodeSeen = 0;
       map.hashCode;
       map.hashCode;
+      expect(hashCodeSpy.hashCodeSeen, 1);
     });
 
     test('compares equal to same instance', () {
@@ -419,15 +422,3 @@ void main() {
 class _A {}
 
 class _ExtendsA extends _A {}
-
-class _HashcodeOnlyOnce {
-  bool hashCodeAllowed = true;
-
-  @override
-  // ignore: hash_and_equals
-  int get hashCode {
-    expect(hashCodeAllowed, isTrue);
-    hashCodeAllowed = false;
-    return 0;
-  }
-}

test/performance.dart

@@ -53,3 +53,14 @@ void expectNotMuchFaster(Function notFastFunction, Function slowFunction) {
       ' Measured: first=${fastStopWatch.elapsedMicroseconds}'
       ' second=${slowStopWatch.elapsedMicroseconds}';
 }
+
+class HashCodeSpy {
+  int hashCodeSeen = 0;
+
+  @override
+  // ignore: hash_and_equals
+  int get hashCode {
+    ++hashCodeSeen;
+    return 0;
+  }
+}

test/set/built_set_test.dart

@@ -132,10 +132,13 @@ void main() {
     });
 
     test('caches hash', () {
-      var set = BuiltSet<Object>([_HashcodeOnlyTwice()]);
+      var hashCodeSpy = HashCodeSpy();
+      var set = BuiltSet<Object>([hashCodeSpy]);
 
+      hashCodeSpy.hashCodeSeen = 0;
       set.hashCode;
       set.hashCode;
+      expect(hashCodeSpy.hashCodeSeen, 1);
     });
 
     test('compares equal to same instance', () {
@@ -452,15 +455,3 @@ void main() {
 class _A {}
 
 class _ExtendsA extends _A {}
-
-class _HashcodeOnlyTwice {
-  int hashCodeAllowed = 2;
-
-  @override
-  // ignore: hash_and_equals
-  int get hashCode {
-    expect(hashCodeAllowed, isNot(0));
-    hashCodeAllowed--;
-    return 0;
-  }
-}

test/set_multimap/built_set_multimap_test.dart

@@ -209,12 +209,15 @@ void main() {
     });
 
     test('caches hash', () {
+      var hashCodeSpy = HashCodeSpy();
       var multimap = BuiltSetMultimap<Object, Object>({
-        1: [_HashcodeOnlyTwice()]
+        1: [hashCodeSpy]
       });
 
+      hashCodeSpy.hashCodeSeen = 0;
       multimap.hashCode;
       multimap.hashCode;
+      expect(hashCodeSpy.hashCodeSeen, 1);
     });
 
     test('compares equal to same instance', () {
@@ -596,18 +599,6 @@ class _A {}
 
 class _ExtendsA extends _A {}
 
-class _HashcodeOnlyTwice {
-  int hashCodeAllowed = 2;
-
-  @override
-  // ignore: hash_and_equals
-  int get hashCode {
-    expect(hashCodeAllowed, isNot(0));
-    hashCodeAllowed--;
-    return 0;
-  }
-}
-
 // All the methods from `SetMultimap` that we care about, to avoid taking a
 // dependency on `quiver`.
 class _SetMultimap<K, V> {