test: Fully cover boxstream.py with tests

secret_handshake/boxstream.py

@@ -53,6 +53,7 @@ def get_stream_pair(  # pylint: disable=too-many-arguments
     decrypt_nonce: bytes,
     encrypt_key: bytes,
     encrypt_nonce: bytes,
+    # We have kwargs here to devour any extra parameters we get, e.g. from the output of SHSCryptoBase.get_box_keys()
     **kwargs: Any,
 ) -> Tuple["UnboxStream", "BoxStream"]:
     """Create a new duplex box stream"""

tests/test_boxstream.py

@@ -22,7 +22,11 @@
 
 """Tests for the box stream"""
 
-from secret_handshake.boxstream import HEADER_LENGTH, BoxStream, UnboxStream
+from asyncio import IncompleteReadError
+
+from pytest_mock import MockerFixture
+
+from secret_handshake.boxstream import HEADER_LENGTH, BoxStream, UnboxStream, get_stream_pair
 
 from .helpers import AsyncBuffer, async_comprehend
 from .test_crypto import CLIENT_ENCRYPT_KEY, CLIENT_ENCRYPT_NONCE
@@ -74,6 +78,18 @@ async def test_unboxstream() -> None:
     assert unbox_stream.closed
 
 
+async def test_unboxstream_header_read_error(mocker: MockerFixture) -> None:
+    """Test that we can handle errors during header read"""
+
+    buffer = AsyncBuffer()
+    mocker.patch.object(buffer, "readexactly", side_effect=IncompleteReadError(b"", HEADER_LENGTH))
+
+    unbox_stream = UnboxStream(buffer, CLIENT_ENCRYPT_KEY, CLIENT_ENCRYPT_NONCE)
+
+    assert await unbox_stream.read() is None
+    assert unbox_stream.closed is True
+
+
 async def test_long_packets() -> None:
     """Test for receiving long packets"""
 
@@ -94,3 +110,28 @@ async def test_long_packets() -> None:
     assert first_packet == data[:4096]
     second_packet = await unbox_stream.read()
     assert second_packet == data[4096:]
+
+
+def test_get_stream_pair() -> None:
+    """Test the get_stream_pair() function"""
+
+    read_buffer = AsyncBuffer()
+    write_buffer = AsyncBuffer()
+
+    read_stream, write_stream = get_stream_pair(
+        read_buffer,
+        write_buffer,
+        decrypt_key=b"d" * 32,
+        decrypt_nonce=b"dnonce",
+        encrypt_key=b"e" * 32,
+        encrypt_nonce=b"enonce",
+    )
+
+    assert isinstance(read_stream, UnboxStream)
+    assert isinstance(write_stream, BoxStream)
+
+    assert read_stream.key == b"d" * 32
+    assert read_stream.nonce == b"dnonce"
+
+    assert write_stream.key == b"e" * 32
+    assert write_stream.nonce == b"enonce"