Add setup action interface

base/test/android/javatests/src/org/chromium/base/test/SetUpTestRule.java

+// Copyright 2017 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+package org.chromium.base.test;
+
+import org.junit.rules.TestRule;
+import org.junit.runners.model.Statement;
+
+/**
+ * Interface to ensure TestRule that implements it specifies if it would run a set-up process
+ * before @Before.
+ *
+ * @param <T> TestRule type that implements this SetUpTestRule
+ */
+public interface SetUpTestRule<T extends TestRule> {
+    /**
+     * Set whether the TestRule should run setUp automatically and return the TestRule.

[mikecase (-- gone --), 2017/03/27 18:40:59]

This could probably use clearer wording. Maybe...

/*
Sets whether the TestRule should run setUp automatically.

@returns itself for convenience
*/

[the real yoland, 2017/03/27 20:52:36]

Done

+     *
+     * So TestRule can be declared in test like this:
+     * <code>
+     * &#064;Rule TestRule mRule = new MySetUpTestRule().shouldSetUp(true);
+     * </code>
+     */
+    T shouldSetUp(boolean runSetUp);
+
+    /**
+     * Specify setUp action in this method
+     */
+    void setUp();
+
+    /**
+     * Custom Statment for SetUpTestRules.
+     *
+     * The statment calls {@link SetUpTestRule#setUp} before test run based on
+     * {@link SetUpTestRule#shouldSetUp} argument
+     */
+    public static class SetUpStatement extends Statement {
+        private final Statement mBase;
+        private final SetUpTestRule<? extends TestRule> mSetUpTestRule;
+        private final boolean mShouldSetUp;
+
+        public SetUpStatement(final Statement base, SetUpTestRule<? extends TestRule> callback,
+                boolean shouldSetUp) {
+            mBase = base;
+            mSetUpTestRule = callback;
+            mShouldSetUp = shouldSetUp;
+        }
+
+        @Override
+        public void evaluate() throws Throwable {
+            if (mShouldSetUp) {
+                mSetUpTestRule.setUp();
+            }
+            mBase.evaluate();
+        }
+    }
+}