Use unix line-endings in bash activate script

Fixes: pypa#1818

Signed-off-by: Siddhant Kumar <skumar619@bloomberg.net>

docs/changelog/1818.bugfix.rst

@@ -0,0 +1 @@
+Use unix style line endings in bash activation script - by :user:`saytosid`.

src/virtualenv/activation/bash/__init__.py

@@ -1,13 +1,34 @@
 from __future__ import absolute_import, unicode_literals
 
+from virtualenv.info import IS_WIN
 from virtualenv.util.path import Path
 
 from ..via_template import ViaTemplateActivator
 
 
 class BashActivator(ViaTemplateActivator):
+    def generate(self, creator):
+        generated = super(BashActivator, self).generate(creator)
+        if IS_WIN:
+            _convert_to_unix_line_endings(generated)
+        return generated
+
     def templates(self):
         yield Path("activate.sh")
 
     def as_name(self, template):
         return template.stem
+
+
+def _convert_to_unix_line_endings(generated):
+    WINDOWS_LINE_ENDING = b"\r\n"
+    UNIX_LINE_ENDING = b"\n"
+
+    for file_path in generated:
+        with open(file_path, "rb") as open_file:
+            content = open_file.read()
+
+        content = content.replace(WINDOWS_LINE_ENDING, UNIX_LINE_ENDING)
+
+        with open(file_path, "wb") as open_file:
+            open_file.write(content)

tests/unit/activation/test_bash.py

@@ -1,13 +1,16 @@
 from __future__ import absolute_import, unicode_literals
 
-import sys
+from unittest.mock import MagicMock
 
 import pytest
 
 from virtualenv.activation import BashActivator
+from virtualenv.activation.via_template import ViaTemplateActivator
+from virtualenv.info import IS_WIN
+from virtualenv.util.path import Path
 
 
-@pytest.mark.skipif(sys.platform == "win32", reason="Github Actions ships with WSL bash")
+@pytest.mark.skipif(IS_WIN, reason="Github Actions ships with WSL bash")
 def test_bash(raise_on_non_source_class, activation_tester):
     class Bash(raise_on_non_source_class):
         def __init__(self, session):
@@ -16,3 +19,20 @@ def __init__(self, session):
             )
 
     activation_tester(Bash)
+
+
+@pytest.mark.skipif(not IS_WIN, reason="Only makes sense on Windows")
+def test_bash_activate_script_has_unix_line_endings(tmpdir):
+    class Mock_ViaTemplateActivator(ViaTemplateActivator):
+        def generate(self, creator):
+            file_path = tmpdir / "activate"
+            with open(file_path, "wb") as windows_line_endings_file:
+                windows_line_endings_file.writelines([b"Test_file\r\n"] * 10)
+
+            return [Path(file_path)]
+
+    class TestBashActivator(BashActivator, Mock_ViaTemplateActivator):
+        pass
+
+    (file_path,) = TestBashActivator(MagicMock()).generate(MagicMock())
+    assert b"\r\n" not in file_path.read_bytes()