Make container classes in SkTemplates.h more consistent

tests/TemplatesTest.cpp

Index: tests/TemplatesTest.cpp
diff --git a/tests/TemplatesTest.cpp b/tests/TemplatesTest.cpp
index 31859f3f0cea620af3868ce26c93a01601be2b20..4698dbb483f27fdefb7860e99ca6a17789f5bdc1 100644
--- a/tests/TemplatesTest.cpp
+++ b/tests/TemplatesTest.cpp
@@ -67,6 +67,38 @@ static void test_automalloc_realloc(skiatest::Reporter* reporter) {
     REPORTER_ASSERT(reporter, array[0] == 1);
 }
 
+constexpr int static kStackPreallocCount = 10;
+
+// Ensures the buffers in SkTemplates.h all have a consistent api.
+template<typename TBuffer> static void test_buffer_apis(skiatest::Reporter* reporter) {
+    REPORTER_ASSERT(reporter, !TBuffer(0lu).get());
+    REPORTER_ASSERT(reporter, TBuffer(1).get());
+    REPORTER_ASSERT(reporter, TBuffer(kStackPreallocCount).get());
+    REPORTER_ASSERT(reporter, TBuffer(kStackPreallocCount + 1).get());
+
+    TBuffer buffer;
+    // The default constructor may or may not init to empty, depending on the type of buffer.
+
+    buffer.reset(1);
+    REPORTER_ASSERT(reporter, buffer.get());
+
+    buffer.reset(kStackPreallocCount);
+    REPORTER_ASSERT(reporter, buffer.get());
+
+    buffer.reset(kStackPreallocCount + 1);
+    REPORTER_ASSERT(reporter, buffer.get());
+
+    buffer.reset(0);
+    REPORTER_ASSERT(reporter, !buffer.get());
+}
+
 DEF_TEST(Templates, reporter) {
     test_automalloc_realloc(reporter);
 }
+
+DEF_TEST(TemplateBuffers, reporter) {
+    test_buffer_apis<SkAutoTArray<int> >(reporter);
+    test_buffer_apis<SkAutoSTArray<kStackPreallocCount, int> >(reporter);
+    test_buffer_apis<SkAutoTMalloc<int> >(reporter);
+    test_buffer_apis<SkAutoSTMalloc<kStackPreallocCount, int> >(reporter);
+}