Changes to SkTDStackNester.

tests/TDStackNesterTest.cpp

Index: tests/TDStackNesterTest.cpp
diff --git a/tests/TDStackNesterTest.cpp b/tests/TDStackNesterTest.cpp
new file mode 100644
index 0000000000000000000000000000000000000000..1dc7e0a9c895d286e71c16a7a40a68e63799477b
--- /dev/null
+++ b/tests/TDStackNesterTest.cpp
@@ -0,0 +1,111 @@
+/*
+ * Copyright 2013 Google Inc.
+ *
+ * Use of this source code is governed by a BSD-style license that can be
+ * found in the LICENSE file.
+ */
+
+#include "SkTDStackNester.h"
+
+#include "Test.h"
+#include "TestClassDef.h"
+
+/**
+ *  Test SkTDStackNester<int>::push(). Pushes the current count onto the stack,
+ *  and checks that the count has increased by one.
+ */
+static void test_push(skiatest::Reporter* reporter, SkTDStackNester<int>* nester) {
+    SkASSERT(nester);
+    const int count = nester->count();
+    // test_pop depends on this value.
+    nester->push(count);
+    REPORTER_ASSERT(reporter, nester->count() == count + 1);
+}
+
+/**
+ *  Test SkTDStackNester<int>::pop(). Pops the top element off the stack, and
+ *  checks that the new count is one smaller, and that the popped element
+ *  matches the new count (as was pushed by test_push).
+ */
+static void test_pop(skiatest::Reporter* reporter, SkTDStackNester<int>* nester) {
+    SkASSERT(nester);
+    const int count = nester->count();
+    // This test should not be called with a count <= 0.
+    SkASSERT(count > 0);
+    const int top = nester->top();
+    int value = -1;
+    nester->pop(&value);
+    REPORTER_ASSERT(reporter, top == value);
+    const int newCount = nester->count();
+    REPORTER_ASSERT(reporter, newCount == count - 1);
+    // Since test_push always pushes the count prior to the push, value should
+    // always be one less than count.
+    REPORTER_ASSERT(reporter, newCount == value);
+}
+
+/**
+ *  Test nest() and unnest(). nest() is called, and it is confirmed that the
+ *  count is now zero. Then test_push() is called inc times, followed by a call to
+ *  unnest(). After this call, check that the count has returned to the initial count, and
+ *  that nestingLevel() has returned to its initial value.
+ */
+static void test_nest(skiatest::Reporter* reporter, SkTDStackNester<int>* nester, int inc) {
+    SkASSERT(nester);
+    SkASSERT(inc > 0);
+    const int initialCount = nester->count();
+    const int initialNesting = nester->nestingLevel();
+
+    nester->nest();
+    REPORTER_ASSERT(reporter, nester->count() == 0);
+    REPORTER_ASSERT(reporter, nester->nestingLevel() == initialNesting + 1);
+
+    for (int i = 0; i < inc; ++i) {
+        test_push(reporter, nester);
+    }
+
+    nester->unnest();
+    REPORTER_ASSERT(reporter, nester->count() == initialCount);
+    REPORTER_ASSERT(reporter, nester->nestingLevel() == initialNesting);
+}
+
+class SkTDStackNesterTester {
+public:
+    static int GetSlotCount() {
+        return SkTDStackNester<int>::kSlotCount;
+    }
+};
+
+static void test_stack_nester(skiatest::Reporter* reporter) {
+    SkTDStackNester<int> nester;
+    int count = nester.count();
+    REPORTER_ASSERT(reporter, 0 == count);
+    REPORTER_ASSERT(reporter, nester.nestingLevel() == 0);
+    REPORTER_ASSERT(reporter, nester.empty());
+
+    // Test nesting (with arbitrary number of pushes) from the beginning.
+    test_nest(reporter, &nester, 3);
+
+    const int slotCount = SkTDStackNesterTester::GetSlotCount();
+
+    // Test pushing beyond the boundary of the first Rec.
+    for (; count < 2 * slotCount; ++count) {
+        if (3 == count) {
+            // Test nesting (an arbitrary number of pushes) early on.
+            test_nest(reporter, &nester, 7);
+        } else if (slotCount - 4 == count) {
+            // Test nesting across the boundary of a Rec.
+            test_nest(reporter, &nester, 6);
+        }
+        test_push(reporter, &nester);
+    }
+
+    // Pop everything off the stack except for the last one, to confirm
+    // that the destructor handles a remaining object.
+    while (nester.count() > 1) {
+        test_pop(reporter, &nester);
+    }
+}
+
+DEF_TEST(TDStackNester, reporter) {
+    test_stack_nester(reporter);
+}