Add a few leak check tests.

These tests are meant to replace the leak check tests from libbacktrace.

Bug: 120606663

Test: Ran tests on host and target.
Change-Id: I928b199304afc36b4bac78e9a2cd688b6f2910b9
diff --git a/libunwindstack/tests/TestUtils.cpp b/libunwindstack/tests/TestUtils.cpp
new file mode 100644
index 0000000..e76f5f8
--- /dev/null
+++ b/libunwindstack/tests/TestUtils.cpp
@@ -0,0 +1,44 @@
+/*
+ * Copyright (C) 2019 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.
+ */
+
+#include <malloc.h>
+#include <stdint.h>
+
+#include <gtest/gtest.h>
+
+namespace unwindstack {
+
+void TestCheckForLeaks(void (*unwind_func)(void*), void* data) {
+  static constexpr size_t kNumLeakLoops = 200;
+  static constexpr size_t kMaxAllowedLeakBytes = 32 * 1024;
+
+  size_t first_allocated_bytes = 0;
+  size_t last_allocated_bytes = 0;
+  for (size_t i = 0; i < kNumLeakLoops; i++) {
+    unwind_func(data);
+
+    size_t allocated_bytes = mallinfo().uordblks;
+    if (first_allocated_bytes == 0) {
+      first_allocated_bytes = allocated_bytes;
+    } else if (last_allocated_bytes > first_allocated_bytes) {
+      // Check that the memory did not increase too much over the first loop.
+      ASSERT_LE(last_allocated_bytes - first_allocated_bytes, kMaxAllowedLeakBytes);
+    }
+    last_allocated_bytes = allocated_bytes;
+  }
+}
+
+}  // namespace unwindstack