1 files changed, 37 insertions, 0 deletions
diff --git a/src/test/java/com/google/devtools/build/lib/testutil/TimestampGranularityUtils.java b/src/test/java/com/google/devtools/build/lib/testutil/TimestampGranularityUtils.java
new file mode 100644
index 0000000000..0f35467935
--- /dev/null
+++ b/src/test/java/com/google/devtools/build/lib/testutil/TimestampGranularityUtils.java
@@ -0,0 +1,37 @@
+// Copyright 2018 The Bazel Authors. 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.testutil;
+
+import com.google.devtools.build.lib.clock.BlazeClock;
+import com.google.devtools.build.lib.util.io.OutErr;
+import com.google.devtools.build.lib.util.io.TimestampGranularityMonitor;
+
+/**
+ * Test utilities that help waiting for the filesystem timestamp granularity.
+ *
+ * <p>It is necessary to wait for the timestamp granularity if a test asserts changes in the mtime
+ * or ctime of a file.
+ */
+public abstract class TimestampGranularityUtils {
+
+  private TimestampGranularityUtils() {}
+
+  /** Wait enough such that changes to a file with the given ctime will have observable effects. */
+  public static void waitForTimestampGranularity(long ctimeMillis, OutErr outErr) {
+    TimestampGranularityMonitor tsgm = new TimestampGranularityMonitor(BlazeClock.instance());
+    tsgm.setCommandStartTime();
+    tsgm.notifyDependenceOnFileTime(null, ctimeMillis);
+    tsgm.waitForTimestampGranularity(outErr);
+  }
+}