Try to handle Windows in making the fake python

conda_lock/conda_solver.py

@@ -9,6 +9,7 @@
 import time
 
 from contextlib import contextmanager
+from textwrap import dedent
 from typing import (
     Any,
     Dict,
@@ -584,37 +585,62 @@ def fake_conda_environment(
         yield prefix
 
 
-FAKE_PYTHON_BINARY = """\
-#!/usr/bin/env python
-
-import sys
-import shlex
-
-cmd = shlex.join(sys.argv)
+def make_fake_python_binary(prefix: str) -> None:
+    """Create a fake python binary in the given prefix.
 
-stderr_message = f'''\
-This is a fake python binary generated by conda-lock.
+    This is intended to prevent failure of `PrefixData.load_site_packages`
+    which was introduced in libmamba v2. That function invokes the command
+    `python -q -m pip inspect --local` to check for installed pip packages,
+    where the `python` binary is the one in the conda prefix. Our fake
+    prefix only contains the package metadata records, not the actual
+    packages or binaries. At this stage for conda-lock, we are only
+    interested in the conda packages, so we spoof the `python` binary
+    to return an empty stdout so that things proceed without error.
+    """
+    # Write the fake Python script to a file
+    fake_python_script = pathlib.Path(prefix) / "fake_python_script.py"
+    fake_python_script.write_text(
+        dedent(
+            """\
+            import sys
+            import shlex
 
-It prevents libmamba from failing when it tries to check for installed pip packages.
+            cmd = shlex.join(sys.argv)
 
-This was called as:
-    {cmd}
-'''
+            stderr_message = f'''\
+            This is a fake python binary generated by conda-lock.
 
-print(stderr_message, file=sys.stderr, flush=True, end='')
+            It prevents libmamba from failing when it tries to check for installed \
+            pip packages.
 
-if "-m pip" not in cmd:
-    raise RuntimeError("Expected to invoke pip module with `-m pip`.")
-"""
+            This was called as:
+                {cmd}
+            '''
 
+            print(stderr_message, file=sys.stderr, flush=True, end='')
 
-def make_fake_python_binary(prefix: str) -> None:
-    """Create a fake python binary in the given prefix.
+            if "-m pip" not in cmd:
+                raise RuntimeError("Expected to invoke pip module with `-m pip`.")
+            """
+        )
+    )
 
-    This is intended to prevent failure of `PrefixData.load_site_packages`
-    which was introduced in libmamba v2.
-    """
-    fake_python_binary = pathlib.Path(prefix) / "bin" / "python"
-    fake_python_binary.parent.mkdir(parents=True, exist_ok=True)
-    fake_python_binary.write_text(FAKE_PYTHON_BINARY)
-    fake_python_binary.chmod(0o755)
+    if sys.platform == "win32":
+        # On Windows, create a batch file that calls the script
+        fake_python_binary = pathlib.Path(prefix) / "Scripts" / "python.bat"
+        fake_python_binary.parent.mkdir(parents=True, exist_ok=True)
+        batch_content = dedent(f"""\
+            @echo off
+            "{sys.executable}" "{fake_python_script}" %*
+        """)
+        fake_python_binary.write_text(batch_content)
+    else:
+        # On Unix-like systems, create a shell script that calls the script
+        fake_python_binary = pathlib.Path(prefix) / "bin" / "python"
+        fake_python_binary.parent.mkdir(parents=True, exist_ok=True)
+        shell_script_content = dedent(f"""\
+            #!/usr/bin/env sh
+            "{sys.executable}" "{fake_python_script}" "$@"
+        """)
+        fake_python_binary.write_text(shell_script_content)
+        fake_python_binary.chmod(0o755)