Extract BytesMemoryCache from MemoryCachingByteStore.

pkg/front_end/test/src/byte_store/byte_store_test.dart

Index: pkg/front_end/test/src/byte_store/byte_store_test.dart
diff --git a/pkg/front_end/test/src/byte_store/byte_store_test.dart b/pkg/front_end/test/src/byte_store/byte_store_test.dart
index 2ebc02450852476582ace553113422df1b300a4f..328377afea36cc2fd685e0469e5dfe55ef01ecf0 100644
--- a/pkg/front_end/test/src/byte_store/byte_store_test.dart
+++ b/pkg/front_end/test/src/byte_store/byte_store_test.dart
@@ -3,12 +3,12 @@
 // BSD-style license that can be found in the LICENSE file.
 
 import 'package:front_end/src/byte_store/byte_store.dart';
-import 'package:mockito/mockito.dart';
 import 'package:test/test.dart';
 import 'package:test_reflective_loader/test_reflective_loader.dart';
 
 main() {
   defineReflectiveSuite(() {
+    defineReflectiveTests(BytesMemoryCacheTest);
     defineReflectiveTests(MemoryCachingByteStoreTest);
     defineReflectiveTests(NullByteStoreTest);
   });
@@ -18,10 +18,91 @@ List<int> _b(int length) {
   return new List<int>(length);
 }
 
+@reflectiveTest
+class BytesMemoryCacheTest {
+  test_get_notFound_evict() {
+    var cache = new BytesMemoryCache(100);
+
+    // Request '1'.  Nothing found.
+    expect(cache.get('1', _noBytes), isNull);
+
+    // Add enough data to the store to force an eviction.
+    cache.put('2', _b(40));
+    cache.put('3', _b(40));
+    cache.put('4', _b(40));
+  }
+
+  test_get_notFound_retry() {
+    var cache = new BytesMemoryCache(100);
+
+    // Request '1'.  Nothing found.
+    expect(cache.get('1', _noBytes), isNull);
+
+    // Request '1' again.
+    // The previous `null` result should not have been cached.
+    expect(cache.get('1', () => _b(40)), isNotNull);
+  }
+
+  test_get_put_evict() {
+    var cache = new BytesMemoryCache(100);
+
+    // Keys: [1, 2].
+    cache.put('1', _b(40));
+    cache.put('2', _b(50));
+
+    // Request '1', so now it is the most recently used.
+    // Keys: [2, 1].
+    cache.get('1', _noBytes);
+
+    // 40 + 50 + 30 > 100
+    // So, '2' is evicted.
+    cache.put('3', _b(30));
+    expect(cache.get('1', _noBytes), hasLength(40));
+    expect(cache.get('2', _noBytes), isNull);
+    expect(cache.get('3', _noBytes), hasLength(30));
+  }
+
+  test_put_evict_first() {
+    var cache = new BytesMemoryCache(100);
+
+    // 40 + 50 < 100
+    cache.put('1', _b(40));
+    cache.put('2', _b(50));
+    expect(cache.get('1', _noBytes), hasLength(40));
+    expect(cache.get('2', _noBytes), hasLength(50));
+
+    // 40 + 50 + 30 > 100
+    // So, '1' is evicted.
+    cache.put('3', _b(30));
+    expect(cache.get('1', _noBytes), isNull);
+    expect(cache.get('2', _noBytes), hasLength(50));
+    expect(cache.get('3', _noBytes), hasLength(30));
+  }
+
+  test_put_evict_firstAndSecond() {
+    var cache = new BytesMemoryCache(100);
+
+    // 10 + 80 < 100
+    cache.put('1', _b(10));
+    cache.put('2', _b(80));
+    expect(cache.get('1', _noBytes), hasLength(10));
+    expect(cache.get('2', _noBytes), hasLength(80));
+
+    // 10 + 80 + 30 > 100
+    // So, '1' and '2' are evicted.
+    cache.put('3', _b(30));
+    expect(cache.get('1', _noBytes), isNull);
+    expect(cache.get('2', _noBytes), isNull);
+    expect(cache.get('3', _noBytes), hasLength(30));
+  }
+
+  static List<int> _noBytes() => null;
+}
+
 @reflectiveTest
 class MemoryCachingByteStoreTest {
   test_get_notFound_evict() {
-    var store = new _TestByteStore();
+    var store = new NullByteStore();
     var cachingStore = new MemoryCachingByteStore(store, 100);
 
     // Request '1'.  Nothing found.
@@ -34,7 +115,7 @@ class MemoryCachingByteStoreTest {
   }
 
   test_get_notFound_retry() {
-    var mockStore = new _TestByteStore();
+    var mockStore = new NullByteStore();
     var baseStore = new MemoryCachingByteStore(mockStore, 1000);
     var cachingStore = new MemoryCachingByteStore(baseStore, 100);
 
@@ -50,7 +131,7 @@ class MemoryCachingByteStoreTest {
   }
 
   test_get_put_evict() {
-    var store = new _TestByteStore();
+    var store = new NullByteStore();
     var cachingStore = new MemoryCachingByteStore(store, 100);
 
     // Keys: [1, 2].
@@ -70,7 +151,7 @@ class MemoryCachingByteStoreTest {
   }
 
   test_put_evict_first() {
-    var store = new _TestByteStore();
+    var store = new NullByteStore();
     var cachingStore = new MemoryCachingByteStore(store, 100);
 
     // 40 + 50 < 100
@@ -88,7 +169,7 @@ class MemoryCachingByteStoreTest {
   }
 
   test_put_evict_firstAndSecond() {
-    var store = new _TestByteStore();
+    var store = new NullByteStore();
     var cachingStore = new MemoryCachingByteStore(store, 100);
 
     // 10 + 80 < 100
@@ -117,5 +198,3 @@ class NullByteStoreTest {
     expect(store.get('1'), isNull);
   }
 }
-
-class _TestByteStore extends Mock implements ByteStore {}