Adds color to ERROR and SUCCESS in check mode.

Fixes PyCQA#1177.

isort/api.py

@@ -7,6 +7,8 @@
 from typing import List, Optional, TextIO, Union, cast
 from warnings import warn
 
+import colorama
+
 from . import io, output, parse
 from .exceptions import (
     ExistingSyntaxErrors,
@@ -19,6 +21,8 @@
     format_natural,
     remove_whitespace,
     show_unified_diff,
+    style_error,
+    style_success,
 )
 from .io import Empty
 from .place import module as place_module  # skipcq: PYL-W0611 (intended export of public API)
@@ -219,10 +223,13 @@ def check_stream(
 
     if not changed:
         if config.verbose:
-            print(f"SUCCESS: {file_path or ''} Everything Looks Good!")
+            print(f"{style_success('SUCCESS')}: {file_path or ''} Everything Looks Good!")
         return True
     else:
-        print(f"ERROR: {file_path or ''} Imports are incorrectly sorted and/or formatted.")
+        print(
+            f"{style_error('ERROR')}: "
+            f"{file_path or ''} Imports are incorrectly sorted and/or formatted."
+        )
         if show_diff:
             output_stream = StringIO()
             input_stream.seek(0)

isort/format.py

@@ -1,8 +1,13 @@
 import sys
 from datetime import datetime
 from difflib import unified_diff
+from functools import partial
 from pathlib import Path
-from typing import Optional, TextIO
+from typing import Iterable, Optional, TextIO
+
+import colorama
+
+colorama.init()
 
 
 def format_simplified(import_line: str) -> str:
@@ -71,3 +76,12 @@ def ask_whether_to_apply_changes_to_file(file_path: str) -> bool:
 def remove_whitespace(content: str, line_separator: str = "\n") -> str:
     content = content.replace(line_separator, "").replace(" ", "").replace("\x0c", "")
     return content
+
+
+def style_text(text: str, styles: Iterable[str]) -> str:
+    escape_sequences = "".join(styles)
+    return escape_sequences + text + colorama.Style.RESET_ALL
+
+
+style_error = partial(style_text, styles=(colorama.Fore.RED,))
+style_success = partial(style_text, styles=(colorama.Fore.GREEN,))

pyproject.toml

@@ -42,6 +42,7 @@ pipreqs = {version = "*", optional = true}
 requirementslib = {version = "*", optional = true}
 tomlkit = {version = ">=0.5.3", optional = true}
 pip-api = {version = "*", optional = true}
+colorama = "^0.4.3"
 
 [tool.poetry.extras]
 pipfile_deprecated_finder = ["pipreqs", "tomlkit", "requirementslib", "pip-shims<=0.3.4"]

tests/test_format.py

@@ -1,5 +1,6 @@
 from unittest.mock import MagicMock, patch
 
+import colorama
 import pytest
 from hypothesis_auto import auto_pytest_magic
 
@@ -16,3 +17,17 @@ def test_ask_whether_to_apply_changes_to_file():
     with patch("isort.format.input", MagicMock(return_value="q")):
         with pytest.raises(SystemExit):
             assert isort.format.ask_whether_to_apply_changes_to_file("")
+
+
+def test_style_error():
+    message = "ERROR"
+    styled = isort.format.style_error(message)
+    assert message in styled
+    assert styled == colorama.Fore.RED + message + colorama.Style.RESET_ALL
+
+
+def test_style_success():
+    message = "OK"
+    styled = isort.format.style_success(message)
+    assert message in styled
+    assert styled == colorama.Fore.GREEN + message + colorama.Style.RESET_ALL

tests/test_isort.py

@@ -2656,7 +2656,8 @@ def test_strict_whitespace_by_default(capsys) -> None:
     test_input = "import os\nfrom django.conf import settings\n"
     assert not api.check_code_string(test_input)
     out, _ = capsys.readouterr()
-    assert out == "ERROR:  Imports are incorrectly sorted and/or formatted.\n"
+    assert "ERROR" in out
+    assert out.endswith("Imports are incorrectly sorted and/or formatted.\n")
 
 
 def test_strict_whitespace_no_closing_newline_issue_676(capsys) -> None: