1 files changed, 79 insertions, 0 deletions
diff --git a/javatests/com/google/android/libraries/mobiledatadownload/file/common/internal/ExponentialBackoffIteratorTest.java b/javatests/com/google/android/libraries/mobiledatadownload/file/common/internal/ExponentialBackoffIteratorTest.java
new file mode 100644
index 0000000..150e043
--- /dev/null
+++ b/javatests/com/google/android/libraries/mobiledatadownload/file/common/internal/ExponentialBackoffIteratorTest.java
@@ -0,0 +1,79 @@
+/*
+ * Copyright 2022 Google LLC
+ *
+ * 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.android.libraries.mobiledatadownload.file.common.internal;
+
+import static com.google.common.truth.Truth.assertThat;
+import static org.junit.Assert.assertThrows;
+
+import androidx.test.ext.junit.runners.AndroidJUnit4;
+import java.util.Iterator;
+import org.junit.Test;
+import org.junit.runner.RunWith;
+
+@RunWith(AndroidJUnit4.class)
+public final class ExponentialBackoffIteratorTest {
+
+  @Test
+  public void testNegativeInitialBackoff() throws Exception {
+    assertThrows(IllegalArgumentException.class, () -> ExponentialBackoffIterator.create(-1, 0));
+  }
+
+  @Test
+  public void testZeroInitialBackoff() throws Exception {
+    assertThrows(IllegalArgumentException.class, () -> ExponentialBackoffIterator.create(0, 0));
+  }
+
+  @Test
+  public void testUpperBoundLessThanInitialBackoff() throws Exception {
+    assertThrows(IllegalArgumentException.class, () -> ExponentialBackoffIterator.create(1, 0));
+  }
+
+  @Test
+  public void testLargeInitialBackoffWillNotOverflow() throws Exception {
+    Iterator<Long> iterator = ExponentialBackoffIterator.create(Long.MAX_VALUE - 1, Long.MAX_VALUE);
+
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(Long.MAX_VALUE - 1);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(Long.MAX_VALUE);
+  }
+
+  @Test
+  public void testExponentialBackoffBackoffs() throws Exception {
+    Iterator<Long> iterator = ExponentialBackoffIterator.create(10, 1000);
+
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(10);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(20);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(40);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(80);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(160);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(320);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(640);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(1000);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(1000);
+    assertThat(iterator.hasNext()).isTrue();
+    assertThat(iterator.next()).isEqualTo(1000);
+  }
+}