aaudio: test MonotonicCounter

Check overflow conditions.
Check basic operation.

Bug: 214726263
Test: atest test_monotonic_counter
Change-Id: Ib5cbc398b236a31dbe7125862f27cc24c86cf435
diff --git a/media/libaaudio/tests/Android.bp b/media/libaaudio/tests/Android.bp
index ea00a5a..4b45909 100644
--- a/media/libaaudio/tests/Android.bp
+++ b/media/libaaudio/tests/Android.bp
@@ -13,6 +13,11 @@
         "-Wall",
         "-Werror",
     ],
+
+    sanitize: {
+        integer_overflow: true,
+        misc_undefined: ["bounds"],
+    },
 }
 
 cc_test {
@@ -146,6 +151,18 @@
     ],
 }
 
+cc_test {
+    name: "test_monotonic_counter",
+    defaults: ["libaaudio_tests_defaults"],
+    srcs: ["test_monotonic_counter.cpp"],
+    shared_libs: [
+        "libaaudio_internal",
+        "libbinder",
+        "libcutils",
+        "libutils",
+    ],
+}
+
 cc_binary {
     name: "test_return_stop",
     defaults: ["libaaudio_tests_defaults"],
diff --git a/media/libaaudio/tests/test_monotonic_counter.cpp b/media/libaaudio/tests/test_monotonic_counter.cpp
new file mode 100644
index 0000000..5cbbaf7
--- /dev/null
+++ b/media/libaaudio/tests/test_monotonic_counter.cpp
@@ -0,0 +1,91 @@
+/*
+ * Copyright 2022 The Android Open Source Project
+ *
+ * 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.
+ */
+
+/*
+ * Test MonotonicCounter
+ */
+
+#include <iostream>
+
+#include <gtest/gtest.h>
+
+#include "utility/MonotonicCounter.h"
+
+TEST(test_monotonic_counter, builtin_wrap) {
+    int32_t x = 0x7FFFFFF0;
+    int32_t y = 0x80000010;
+    int32_t delta;
+    // delta = y - x; // This would cause a numeric overflow!
+    __builtin_sub_overflow(y, x, &delta);
+    ASSERT_EQ(0x20, delta);
+}
+
+// test updating past some overflow points
+TEST(test_monotonic_counter, mono_counter_update32_wrap) {
+    MonotonicCounter counter;
+    ASSERT_EQ(0, counter.get());
+
+    static constexpr uint32_t x = (uint32_t) 0x7FFFFFF0;
+    counter.update32(x);
+    ASSERT_EQ((int64_t)0x7FFFFFF0, counter.get());
+
+    static constexpr uint32_t y = (uint32_t) 0x80000010;
+    counter.update32(y);
+    ASSERT_EQ((int64_t)0x80000010, counter.get());
+
+    counter.update32(0);
+    ASSERT_EQ((int64_t)0x100000000, counter.get());
+}
+
+TEST(test_monotonic_counter, mono_counter_roundup) {
+    MonotonicCounter counter;
+    static constexpr uint32_t x = 2345;
+    counter.update32(x);
+    ASSERT_EQ((int64_t)x, counter.get());
+
+    counter.roundUp64(100);
+    ASSERT_EQ((int64_t)2400, counter.get());
+}
+
+TEST(test_monotonic_counter, mono_counter_catchup) {
+    MonotonicCounter counter;
+    counter.update32(7654);
+    counter.catchUpTo(5000); // already past 5000 so no change
+    ASSERT_EQ((int64_t)7654, counter.get());
+    counter.catchUpTo(9876); // jumps
+    ASSERT_EQ((int64_t)9876, counter.get());
+}
+
+TEST(test_monotonic_counter, mono_counter_increment) {
+    MonotonicCounter counter;
+    counter.update32(1000);
+    counter.increment(-234); // will not go backwards
+    ASSERT_EQ((int64_t)1000, counter.get());
+    counter.increment(96); // advances
+    ASSERT_EQ((int64_t)1096, counter.get());
+}
+
+TEST(test_monotonic_counter, mono_counter_reset) {
+    MonotonicCounter counter;
+    counter.update32(1000);
+    // Counter is monotonic and should not go backwards.
+    counter.update32(500); // No change because 32-bit counter is already past 1000.
+    ASSERT_EQ((int64_t)1000, counter.get());
+
+    counter.reset32();
+    counter.update32(500);
+    ASSERT_EQ((int64_t)1500, counter.get());
+}