SkBlockMemoryStream implements peek()

tests/StreamTest.cpp

Index: tests/StreamTest.cpp
diff --git a/tests/StreamTest.cpp b/tests/StreamTest.cpp
index 3641f3b8241babe008b83b55b26bf2657139e044..6bc187109f39e4c1b6393dbf3fa3143e12f739a9 100644
--- a/tests/StreamTest.cpp
+++ b/tests/StreamTest.cpp
@@ -273,3 +273,62 @@ DEF_TEST(StreamPeek, reporter) {
     }
 }
 #endif 
+
+// Asserts that asset == expected and is peekable.
+static void stream_peek_test(skiatest::Reporter*rep,
+                             SkStreamAsset* asset,
+                             const SkData* expected) {
+    if (asset->getLength() != expected->size()) {
+        ERRORF(rep, "Unexpected length.");
+        return;
+    }
+    SkRandom rand;
+    uint8_t buffer[4096];
+    const uint8_t* expect = expected->bytes();
+    for (unsigned i = 0; i < asset->getLength(); ++i) {
+        size_t size = (rand.nextU() % sizeof(buffer)) + 1;

[scroggo, 2015/05/20 15:43:35]

Why not rand.nextRangeU(1, sizeof(buffer))?

[hal.canary, 2015/05/21 13:28:02]

Done.

+        size = SkTMin(size, asset->getLength() - i);
+        if (size > 0) {

[scroggo, 2015/05/20 15:43:35]

Can size ever be 0? I guess with an empty asset? It does not look like we ever
create one. (Though if we did, it seems like this test would fail below when we
try to read it.)

[hal.canary, 2015/05/21 13:28:02]

Done.

Of course size is always > 0!

+            SkASSERT(size <= sizeof(buffer));
+            if (!asset->peek(buffer, size)) {
+                ERRORF(rep, "Peek Failed!");
+                return;
+            }
+            if (0 != memcmp(buffer, &expect[i], size)) {
+                ERRORF(rep, "Peek returned wrong bytes!");
+                return;
+            }
+        }
+        uint8_t value;
+        asset->read(&value, 1);

[scroggo, 2015/05/20 15:43:35]

Check the return value too?

[hal.canary, 2015/05/21 13:28:02]

Done.

+        if (value != expect[i])  {
+            ERRORF(rep, "Read Failed!");
+            return;
+        }
+    }
+}
+
+DEF_TEST(StreamPeek_BlockMemoryStream, rep) {
+    const static int kSeed = 1234;
+    SkRandom valueSource(kSeed);
+    SkRandom rand(kSeed << 1);
+    uint8_t buffer[4096];
+    SkDynamicMemoryWStream dynamicMemoryWStream;
+    for (int i = 0; i < 32; ++i) {
+        // Randomize the length of the blocks.
+        size_t size = (rand.nextU() % sizeof(buffer)) + 1;
+        SkASSERT(size <= sizeof(buffer));
+        for (unsigned j = 0; j < size; ++j) {
+            buffer[j] = valueSource.nextU() & 0xFF;
+        }
+        dynamicMemoryWStream.write(buffer, size);
+    }
+    SkAutoTDelete<SkStreamAsset> asset(dynamicMemoryWStream.detachAsStream());
+    SkAutoTUnref<SkData> expected(SkData::NewUninitialized(asset->getLength()));
+    uint8_t* expectedPtr = static_cast<uint8_t*>(expected->writable_data());
+    valueSource.setSeed(kSeed);  // reseed.

[scroggo, 2015/05/20 15:43:35]

So if I understand correctly, you're just trying to get the same random string
of numbers to put in expected?

[hal.canary, 2015/05/21 13:28:02]

Acknowledged.

+    for (unsigned i = 0; i < asset->getLength(); ++i) {
+        expectedPtr[i] = valueSource.nextU() & 0xFF;
+    }
+    stream_peek_test(rep, asset, expected);
+}