Make test_no_color use output that actually has colors

Also, reflects that `--no-color` does not mean no-ansi-escapes.

Author: pradyunsg

tests/functional/test_no_color.py

@@ -2,14 +2,17 @@
 Test specific for the --no-color option
 """
 import os
+import shutil
 import subprocess
+import sys
 
 import pytest
 
-from tests.lib import PipTestEnvironment
+from tests.lib import PipTestEnvironment, TestData
 
 
-def test_no_color(script: PipTestEnvironment) -> None:
+@pytest.mark.skipif(shutil.which("script") is None, reason="no 'script' executable")
+def test_no_color(script: PipTestEnvironment, data: TestData) -> None:
     """Ensure colour output disabled when --no-color is passed."""
     # Using 'script' in this test allows for transparently testing pip's output
     # since pip is smart enough to disable colour output when piped, which is
@@ -19,12 +22,14 @@ def test_no_color(script: PipTestEnvironment) -> None:
     # 'script' and well as the mere use of the same.
     #
     # This test will stay until someone has the time to rewrite it.
-    command = (
-        "script --flush --quiet --return /tmp/pip-test-no-color.txt "
-        '--command "pip uninstall {} noSuchPackage"'
-    )
+    package = str(data.src / "pep518_invalid_build_system")
+    pip_command = f"pip install --no-index {{}} {package}"
+    if sys.platform == "darwin":
+        command = f"script -q /tmp/pip-test-no-color.txt {pip_command}"
+    else:
+        command = f'script -q /tmp/pip-test-no-color.txt --command "{pip_command}"'
 
-    def get_run_output(option: str) -> str:
+    def get_run_output(option: str = "") -> str:
         cmd = command.format(option)
         proc = subprocess.Popen(
             cmd,
@@ -33,8 +38,6 @@ def get_run_output(option: str) -> str:
             stderr=subprocess.PIPE,
         )
         proc.communicate()
-        if proc.returncode:
-            pytest.skip("Unable to capture output using script: " + cmd)
 
         try:
             with open("/tmp/pip-test-no-color.txt") as output_file:
@@ -43,7 +46,5 @@ def get_run_output(option: str) -> str:
         finally:
             os.unlink("/tmp/pip-test-no-color.txt")
 
-    assert "\x1b" in get_run_output(option=""), "Expected color in output"
-    assert "\x1b" not in get_run_output(
-        option="--no-color"
-    ), "Expected no color in output"
+    assert "\x1b[3" in get_run_output(""), "Expected color in output"
+    assert "\x1b[3" not in get_run_output("--no-color"), "Expected no color in output"