Fix missing coverage

3 files changed, 40 insertions, 10 deletions

diff --git a/tests/unit/test_isort.py b/tests/unit/test_isort.py
index 2cbc93a4..ec2fd5d6 100644
--- a/tests/unit/test_isort.py
+++ b/tests/unit/test_isort.py
@@ -19,6 +19,7 @@ from isort import api, sections, files
 from isort.settings import WrapModes, Config
 from isort.utils import exists_case_sensitive
 from isort.exceptions import FileSkipped, ExistingSyntaxErrors
+from .utils import as_stream, UnreadableStream
 
 TEST_DEFAULT_CONFIG = """
 [*.{py,pyi}]
@@ -1368,6 +1369,7 @@ def test_single_multiline() -> None:
 
 
 def test_atomic_mode() -> None:
+    """With atomic mode isort should be able to automatically detect and stop syntax errors"""
     # without syntax error, everything works OK
     test_input = "from b import d, c\nfrom a import f, e\n"
     assert isort.code(test_input, atomic=True) == ("from a import e, f\nfrom b import c, d\n")
@@ -1377,6 +1379,13 @@ def test_atomic_mode() -> None:
     with pytest.raises(ExistingSyntaxErrors):
         isort.code(test_input, atomic=True)
 
+    # ensure atomic works with streams
+    test_input = as_stream("from b import d, c\nfrom a import f, e\n")
+    test_output = UnreadableStream()
+    isort.stream(test_input, test_output, atomic=True)
+    test_output.seek(0)
+    assert test_output.read() == "from a import e, f\nfrom b import c, d\n"
+
 
 def test_order_by_type() -> None:
     test_input = "from module import Class, CONSTANT, function"
diff --git a/tests/unit/test_main.py b/tests/unit/test_main.py
index ccf51c0e..207f19dc 100644
--- a/tests/unit/test_main.py
+++ b/tests/unit/test_main.py
@@ -2,7 +2,6 @@ import json
 import os
 import subprocess
 from datetime import datetime
-from io import BytesIO, TextIOWrapper
 
 import py
 import pytest
@@ -14,15 +13,8 @@ from isort._version import __version__
 from isort.exceptions import InvalidSettingsPath
 from isort.settings import DEFAULT_CONFIG, Config
 from isort.wrap_modes import WrapModes
-
-
-class UnseekableTextIOWrapper(TextIOWrapper):
-    def seek(self, *args, **kwargs):
-        raise ValueError("underlying stream is not seekable")
-
-
-def as_stream(text: str) -> UnseekableTextIOWrapper:
-    return UnseekableTextIOWrapper(BytesIO(text.encode("utf8")))
+from .utils import as_stream
+from io import BytesIO, TextIOWrapper
 
 
 @given(
@@ -910,6 +902,19 @@ import b
 """
     )
 
+    atomic_input_without_skip = input_with_skip.replace("isort: skip_file", "generic comment")
+    stream_without_skip = as_stream(atomic_input_without_skip)
+    main.main(["-", "--atomic"], stdin=stream_without_skip)
+    out, error = capsys.readouterr()
+    assert (
+        out
+        == """
+# generic comment
+import a
+import b
+"""
+    )
+
 
 def test_only_modified_flag(tmpdir, capsys):
     # ensures there is no verbose output for correct files with only-modified flag
diff --git a/tests/unit/utils.py b/tests/unit/utils.py
index 9c963d63..b87e7a45 100644
--- a/tests/unit/utils.py
+++ b/tests/unit/utils.py
@@ -1,6 +1,22 @@
+from io import BytesIO, StringIO, TextIOWrapper
+
 import isort
 
 
+class UnseekableTextIOWrapper(TextIOWrapper):
+    def seek(self, *args, **kwargs):
+        raise ValueError("underlying stream is not seekable")
+
+
+class UnreadableStream(StringIO):
+    def readable(self, *args, **kwargs) -> bool:
+        return False
+
+
+def as_stream(text: str) -> UnseekableTextIOWrapper:
+    return UnseekableTextIOWrapper(BytesIO(text.encode("utf8")))
+
+
 def isort_test(code: str, expected_output: str = "", **config):
     """Runs isort against the given code snippet and ensures that it
     gives consistent output accross multiple runs, and if an expected_output