Fixes #1033 - Ensure that text that spans 3 invocations before newline is handled - don't clobber the buffer between invocations that haven't seen any lines. (#1034)

Fixes #1033 - Ensure that text that spans 3 invocations before newline is handled - don't clobber the buffer between invocations that haven't seen any lines.

httpx/_decoders.py

@@ -261,7 +261,7 @@ class LineDecoder:
                     text = text[idx + 1 :]
                     break
                 elif next_char is None:
-                    self.buffer = text
+                    self.buffer += text
                     text = ""
                     break
 

requirements.txt

@@ -31,4 +31,4 @@ trustme
 uvicorn
 seed-isort-config
 
-attrs>=19.2  # See: https://github.com/encode/httpx/pull/566#issuecomment-559862665
+attrs>=19.3.0  # See: https://github.com/encode/httpx/pull/566#issuecomment-559862665

tests/test_decoders.py

@@ -225,6 +225,15 @@ def test_line_decoder_nl():
     assert decoder.decode("a\n\nb\nc\n") == ["a\n", "\n", "b\n", "c\n"]
     assert decoder.flush() == []
 
+    # Issue #1033
+    decoder = LineDecoder()
+    assert decoder.decode("") == []
+    assert decoder.decode("12345\n") == ["12345\n"]
+    assert decoder.decode("foo ") == []
+    assert decoder.decode("bar ") == []
+    assert decoder.decode("baz\n") == ["foo bar baz\n"]
+    assert decoder.flush() == []
+
 
 def test_line_decoder_cr():
     decoder = LineDecoder()
@@ -237,6 +246,16 @@ def test_line_decoder_cr():
     assert decoder.decode("a\r\rb\rc\r") == ["a\n", "\n", "b\n"]
     assert decoder.flush() == ["c\n"]
 
+    # Issue #1033
+    # TODO: This seems like another bug; fix expectations and results.
+    decoder = LineDecoder()
+    assert decoder.decode("") == []
+    assert decoder.decode("12345\r") == []
+    assert decoder.decode("foo ") == []
+    assert decoder.decode("bar ") == []
+    assert decoder.decode("baz\r") == []
+    assert decoder.flush() == ["12345\rfoo bar baz\n"]
+
 
 def test_line_decoder_crnl():
     decoder = LineDecoder()
@@ -255,6 +274,15 @@ def test_line_decoder_crnl():
     assert decoder.decode("\n\r\nb\r\nc") == ["a\n", "\n", "b\n"]
     assert decoder.flush() == ["c"]
 
+    # Issue #1033
+    decoder = LineDecoder()
+    assert decoder.decode("") == []
+    assert decoder.decode("12345\r\n") == ["12345\n"]
+    assert decoder.decode("foo ") == []
+    assert decoder.decode("bar ") == []
+    assert decoder.decode("baz\r\n") == ["foo bar baz\n"]
+    assert decoder.flush() == []
+
 
 def test_invalid_content_encoding_header():
     headers = [(b"Content-Encoding", b"invalid-header")]