1 files changed, 75 insertions, 0 deletions
diff --git a/tests/codec/test_streaming.py b/tests/codec/test_streaming.py
new file mode 100644
index 0000000..c608b11
--- /dev/null
+++ b/tests/codec/test_streaming.py
@@ -0,0 +1,75 @@
+#
+# This file is part of pyasn1 software.
+#
+# Copyright (c) 2005-2019, Ilya Etingof <etingof@gmail.com>
+# License: http://snmplabs.com/pyasn1/license.html
+#
+import io
+import sys
+
+try:
+    import unittest2 as unittest
+
+except ImportError:
+    import unittest
+
+from tests.base import BaseTestCase
+
+from pyasn1.codec import streaming
+
+
+class CachingStreamWrapperTestCase(BaseTestCase):
+    def setUp(self):
+        self.shortText = b"abcdefghij"
+        self.longText = self.shortText * (io.DEFAULT_BUFFER_SIZE * 5)
+        self.shortStream = io.BytesIO(self.shortText)
+        self.longStream = io.BytesIO(self.longText)
+
+    def testReadJustFromCache(self):
+        wrapper = streaming.CachingStreamWrapper(self.shortStream)
+        wrapper.read(6)
+        wrapper.seek(3)
+        assert wrapper.read(1) == b"d"
+        assert wrapper.read(1) == b"e"
+        assert wrapper.tell() == 5
+
+    def testReadFromCacheAndStream(self):
+        wrapper = streaming.CachingStreamWrapper(self.shortStream)
+        wrapper.read(6)
+        wrapper.seek(3)
+        assert wrapper.read(4) == b"defg"
+        assert wrapper.tell() == 7
+
+    def testReadJustFromStream(self):
+        wrapper = streaming.CachingStreamWrapper(self.shortStream)
+        assert wrapper.read(6) == b"abcdef"
+        assert wrapper.tell() == 6
+
+    def testPeek(self):
+        wrapper = streaming.CachingStreamWrapper(self.longStream)
+        read_bytes = wrapper.peek(io.DEFAULT_BUFFER_SIZE + 73)
+        assert len(read_bytes) == io.DEFAULT_BUFFER_SIZE + 73
+        assert read_bytes.startswith(b"abcdefg")
+        assert wrapper.tell() == 0
+        assert wrapper.read(4) == b"abcd"
+
+    def testMarkedPositionResets(self):
+        wrapper = streaming.CachingStreamWrapper(self.longStream)
+        wrapper.read(10)
+        wrapper.markedPosition = wrapper.tell()
+        assert wrapper.markedPosition == 10
+
+        # Reach the maximum capacity of cache
+        wrapper.read(io.DEFAULT_BUFFER_SIZE)
+        assert wrapper.tell() == 10 + io.DEFAULT_BUFFER_SIZE
+
+        # The following should clear the cache
+        wrapper.markedPosition = wrapper.tell()
+        assert wrapper.markedPosition == 0
+        assert len(wrapper._cache.getvalue()) == 0
+
+
+suite = unittest.TestLoader().loadTestsFromModule(sys.modules[__name__])
+
+if __name__ == '__main__':
+    unittest.TextTestRunner(verbosity=2).run(suite)