Migrate the shim test to Python

tests/test_shim.py

@@ -0,0 +1,62 @@
+import os
+import shutil
+import subprocess
+import sys
+
+import pytest
+
+
+def which(name):
+    """Find an executable.
+
+    Python 2.7 doesn't have shutil.which().
+    shutil.which() is used, if possible, to handle Windows' case-insensitivity.
+    """
+
+    if hasattr(shutil, "which"):
+        return shutil.which(name)
+
+    for path in os.environ["PATH"].split(os.pathsep):
+        if os.path.isfile(os.path.join(path, name)):
+            return os.path.join(path, name)
+
+
+def test_shim(root, home, dotfiles, run_dotbot):
+    """Verify install shim works."""
+
+    # Skip the test if git is unavailable.
+    git = which("git")
+    if git is None:
+        pytest.skip("git is unavailable")
+
+    if sys.platform[:5] == "win32":
+        install = os.path.join(
+            dotfiles.directory, "dotbot", "tools", "git-submodule", "install.ps1"
+        )
+        shim = os.path.join(dotfiles.directory, "install.ps1")
+    else:
+        install = os.path.join(dotfiles.directory, "dotbot", "tools", "git-submodule", "install")
+        shim = os.path.join(dotfiles.directory, "install")
+
+    # Set up the test environment.
+    git_directory = os.path.dirname(os.path.dirname(os.path.abspath(__file__)))
+    os.chdir(dotfiles.directory)
+    subprocess.check_call([git, "init"])
+    subprocess.check_call([git, "submodule", "add", git_directory, "dotbot"])
+    shutil.copy(install, shim)
+    dotfiles.write("foo", "pear")
+    dotfiles.write_config([{"link": {"~/.foo": "foo"}}])
+
+    # Run the shim script.
+    env = dict(os.environ)
+    if sys.platform[:5] == "win32":
+        args = [which("powershell"), "-ExecutionPolicy", "RemoteSigned", shim]
+        env["USERPROFILE"] = home
+    else:
+        args = [shim]
+        env["HOME"] = home
+    subprocess.check_call(args, env=env, cwd=dotfiles.directory)
+
+    assert os.path.islink(os.path.join(home, ".foo"))
+    with open(os.path.join(home, ".foo"), "r") as file:
+        assert file.read() == "pear"