added unit test for InputReader::try_unread

1 files changed, 26 insertions, 0 deletions

diff --git a/vespalib/src/tests/data/input_reader/input_reader_test.cpp b/vespalib/src/tests/data/input_reader/input_reader_test.cpp
index e8098b7e3ea..c74b16400df 100644
--- a/vespalib/src/tests/data/input_reader/input_reader_test.cpp
+++ b/vespalib/src/tests/data/input_reader/input_reader_test.cpp
@@ -112,4 +112,30 @@ TEST("expect that obtain does not set failure state on input reader") {
     }
 }
 
+TEST("require that bytes can be unread when appropriate") {
+    const char *data = "12345";
+    MemoryInput memory_input(data);
+    ChunkedInput input(memory_input, 3);
+    InputReader src(input);
+    EXPECT_TRUE(!src.try_unread());
+    EXPECT_EQUAL(src.read(), '1');
+    EXPECT_EQUAL(src.read(), '2');
+    EXPECT_EQUAL(src.read(), '3');
+    EXPECT_TRUE(src.try_unread());
+    EXPECT_TRUE(src.try_unread());
+    EXPECT_TRUE(src.try_unread());
+    EXPECT_TRUE(!src.try_unread());
+    EXPECT_EQUAL(src.read(), '1');
+    EXPECT_EQUAL(src.read(), '2');
+    EXPECT_EQUAL(src.read(), '3');
+    EXPECT_EQUAL(src.read(), '4');
+    EXPECT_TRUE(src.try_unread());
+    EXPECT_TRUE(!src.try_unread());
+    EXPECT_EQUAL(src.read(), '4');
+    EXPECT_EQUAL(src.read(), '5');
+    EXPECT_EQUAL(src.obtain(), 0u);
+    EXPECT_TRUE(!src.try_unread());
+    EXPECT_TRUE(!src.failed());
+}
+
 TEST_MAIN() { TEST_RUN_ALL(); }