1 files changed, 76 insertions, 0 deletions
diff --git a/src/test/java/com/google/devtools/build/lib/analysis/util/ActionTester.java b/src/test/java/com/google/devtools/build/lib/analysis/util/ActionTester.java
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+// Copyright 2015 Google Inc. All rights reserved.
+//
+// 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 com.google.devtools.build.lib.analysis.util;
+
+import static com.google.common.truth.Truth.assertThat;
+import static com.google.common.truth.Truth.assertWithMessage;
+
+import com.google.devtools.build.lib.actions.Action;
+import com.google.devtools.build.lib.actions.Actions;
+
+/**
+ * Test helper for testing {@link Action} implementations.
+ */
+public class ActionTester {
+
+  /**
+   * A generator for action instances.
+   */
+  public interface ActionCombinationFactory {
+
+    /**
+     * Returns a new action instance. The parameter {@code i} is used to vary the parameters used to
+     * create the action. Implementations should do something like this:
+     * <code><pre>
+     * return new MyAction(owner, inputs, outputs, configuration,
+     *     (i & 1) == 0 ? a1 : a2,
+     *     (i & 2) == 0 ? b1 : b2,
+     *     (i & 4) == 0 ? c1 : c2);
+     *     (i & 16) == 0 ? d1 : d2);
+     * </pre></code>
+     *
+     * <p>The wrap-around (in this case at 32) is intentional and is checked for by the testing
+     * method.
+     *
+     * <p>To reduce the combinatorial complexity of testing an action class, all elements that are
+     * only used to change the executed command line should go into a single parameter, and the key
+     * computation should take the generated command line into account.
+     *
+     * <p>Furthermore, when called with identical parameters, this method should return different
+     * instances (i.e. according to {@code ==}), but they should have the same key.
+     */
+    Action generate(int i);
+  }
+
+  /**
+   * Tests that different actions have different keys. The count should specify how many different
+   * permutations the {@link ActionCombinationFactory} can generate.
+   */
+  public static void runTest(int count, ActionCombinationFactory factory) throws Exception {
+    Action[] actions = new Action[count];
+    for (int i = 0; i < actions.length; i++) {
+      actions[i] = factory.generate(i);
+    }
+    // Sanity check that the count is correct.
+    assertThat(Actions.canBeShared(actions[0], factory.generate(count))).isTrue();
+
+    for (int i = 0; i < actions.length; i++) {
+      assertThat(Actions.canBeShared(actions[i], factory.generate(i))).isTrue();
+      for (int j = i + 1; j < actions.length; j++) {
+        assertWithMessage(i + " and " + j).that(Actions.canBeShared(actions[i], actions[j]))
+            .isFalse();
+      }
+    }
+  }
+}