Windows: fix pwsh env activate/deactivate; load/unload (#39118)

These commands are currently broken on powershell (Windows) due to
improper use of the InvokeCommand commandlet and a lack of direct
support for the `--pwsh` argument in `spack load`, `spack unload`,
and `spack env deactivate`.

lib/spack/spack/cmd/env.py

@@ -239,6 +239,13 @@ def env_deactivate_setup_parser(subparser):
         const="bat",
         help="print bat commands to activate the environment",
     )
+    shells.add_argument(
+        "--pwsh",
+        action="store_const",
+        dest="shell",
+        const="pwsh",
+        help="print pwsh commands to activate the environment",
+    )
 
 
 def env_deactivate(args):

lib/spack/spack/cmd/load.py

@@ -52,6 +52,13 @@ def setup_parser(subparser):
         const="bat",
         help="print bat commands to load the package",
     )
+    shells.add_argument(
+        "--pwsh",
+        action="store_const",
+        dest="shell",
+        const="pwsh",
+        help="print pwsh commands to load the package",
+    )
 
     subparser.add_argument(
         "--first",

lib/spack/spack/cmd/unload.py

@@ -51,6 +51,13 @@ def setup_parser(subparser):
         const="bat",
         help="print bat commands to load the package",
     )
+    shells.add_argument(
+        "--pwsh",
+        action="store_const",
+        dest="shell",
+        const="pwsh",
+        help="print pwsh commands to load the package",
+    )
 
     subparser.add_argument(
         "-a", "--all", action="store_true", help="unload all loaded Spack packages"

lib/spack/spack/environment/shell.py

@@ -43,7 +43,7 @@ def activate_header(env, shell, prompt=None):
         # TODO: despacktivate
         # TODO: prompt
     elif shell == "pwsh":
-        cmds += "$Env:SPACK_ENV=%s\n" % env.path
+        cmds += "$Env:SPACK_ENV='%s'\n" % env.path
     else:
         if "color" in os.getenv("TERM", "") and prompt:
             prompt = colorize("@G{%s}" % prompt, color=True, enclose=True)
@@ -82,7 +82,7 @@ def deactivate_header(shell):
         # TODO: despacktivate
         # TODO: prompt
     elif shell == "pwsh":
-        cmds += "Remove-Item Env:SPACK_ENV"
+        cmds += "Set-Item -Path Env:SPACK_ENV\n"
     else:
         cmds += "if [ ! -z ${SPACK_ENV+x} ]; then\n"
         cmds += "unset SPACK_ENV; export SPACK_ENV;\n"

lib/spack/spack/test/util/environment.py

@@ -172,8 +172,8 @@ def test_escape_double_quotes_in_shell_modifications():
         assert r'set "VAR=$PATH;$ANOTHER_PATH"' in cmds
         assert r'set "QUOTED_VAR="MY_VAL"' in cmds
         cmds = to_validate.shell_modifications(shell="pwsh")
-        assert r"$Env:VAR=$PATH;$ANOTHER_PATH" in cmds
-        assert r'$Env:QUOTED_VAR="MY_VAL"' in cmds
+        assert "$Env:VAR='$PATH;$ANOTHER_PATH'" in cmds
+        assert "$Env:QUOTED_VAR='\"MY_VAL\"'" in cmds
     else:
         cmds = to_validate.shell_modifications()
         assert 'export VAR="$PATH:$ANOTHER_PATH"' in cmds

lib/spack/spack/util/environment.py

@@ -47,7 +47,7 @@
     "csh": "setenv {0} {1};\n",
     "fish": "set -gx {0} {1};\n",
     "bat": 'set "{0}={1}"\n',
-    "pwsh": "$Env:{0}={1}\n",
+    "pwsh": "$Env:{0}='{1}'\n",
 }
 
 
@@ -56,7 +56,7 @@
     "csh": "unsetenv {0};\n",
     "fish": "set -e {0};\n",
     "bat": 'set "{0}="\n',
-    "pwsh": "Remove-Item Env:{0}\n",
+    "pwsh": "Set-Item -Path Env:{0}\n",
 }
 
 
@@ -429,7 +429,7 @@ class RemovePath(NameValueModifier):
     def execute(self, env: MutableMapping[str, str]):
         tty.debug(f"RemovePath: {self.name}-{str(self.value)}", level=3)
         environment_value = env.get(self.name, "")
-        directories = environment_value.split(self.separator) if environment_value else []
+        directories = environment_value.split(self.separator)
         directories = [
             path_to_os_path(os.path.normpath(x)).pop()
             for x in directories
@@ -724,11 +724,10 @@ def shell_modifications(
                     cmds += _SHELL_UNSET_STRINGS[shell].format(name)
                 else:
                     if sys.platform != "win32":
-                        cmd = _SHELL_SET_STRINGS[shell].format(
-                            name, double_quote_escape(new_env[name])
-                        )
+                        new_env_name = double_quote_escape(new_env[name])
                     else:
-                        cmd = _SHELL_SET_STRINGS[shell].format(name, new_env[name])
+                        new_env_name = new_env[name]
+                    cmd = _SHELL_SET_STRINGS[shell].format(name, new_env_name)
                     cmds += cmd
         return cmds