1 files changed, 65 insertions, 0 deletions
diff --git a/testing/src/test/java/io/opencensus/testing/common/TestClockTest.java b/testing/src/test/java/io/opencensus/testing/common/TestClockTest.java
new file mode 100644
index 00000000..24cd7fcd
--- /dev/null
+++ b/testing/src/test/java/io/opencensus/testing/common/TestClockTest.java
@@ -0,0 +1,65 @@
+/*
+ * Copyright 2017, OpenCensus Authors
+ *
+ * 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 io.opencensus.testing.common;
+
+import static com.google.common.truth.Truth.assertThat;
+
+import io.opencensus.common.Duration;
+import io.opencensus.common.Timestamp;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+import org.junit.runners.JUnit4;
+
+/** Tests for {@link TestClock}. */
+@RunWith(JUnit4.class)
+public final class TestClockTest {
+  private static final int NUM_NANOS_PER_SECOND = 1000 * 1000 * 1000;
+
+  @Test
+  public void setAndGetTime() {
+    TestClock clock = TestClock.create(Timestamp.create(1, 2));
+    assertThat(clock.now()).isEqualTo(Timestamp.create(1, 2));
+    clock.setTime(Timestamp.create(3, 4));
+    assertThat(clock.now()).isEqualTo(Timestamp.create(3, 4));
+  }
+
+  @Test
+  public void advanceTime() {
+    TestClock clock = TestClock.create(Timestamp.create(1, 500 * 1000 * 1000));
+    clock.advanceTime(Duration.create(2, 600 * 1000 * 1000));
+    assertThat(clock.now()).isEqualTo(Timestamp.create(4, 100 * 1000 * 1000));
+  }
+
+  @Test
+  public void measureElapsedTime() {
+    TestClock clock = TestClock.create(Timestamp.create(10, 1));
+    long nanos1 = clock.nowNanos();
+    clock.setTime(Timestamp.create(11, 5));
+    long nanos2 = clock.nowNanos();
+    assertThat(nanos2 - nanos1).isEqualTo(1000 * 1000 * 1000 + 4);
+  }
+
+  @Test(expected = ArithmeticException.class)
+  public void catchOverflow() {
+    TestClock.create(Timestamp.create(Long.MAX_VALUE / NUM_NANOS_PER_SECOND + 1, 0));
+  }
+
+  @Test(expected = ArithmeticException.class)
+  public void catchNegativeOverflow() {
+    TestClock.create(Timestamp.create(Long.MIN_VALUE / NUM_NANOS_PER_SECOND - 1, 0));
+  }
+}