Windows/Testing: enable spack view tests on Windows (#46335)

Enable tests for symlink-based views (this works with almost no
modifications to the view logic). View logic is not yet robust
for hardlink/junction-based views, so those are disabled for now
(both in the tests and as subcommands to `spack view`).

lib/spack/spack/cmd/view.py

@@ -33,6 +33,8 @@
 YamlFilesystemView.
 
 """
+import sys
+
 import llnl.util.tty as tty
 from llnl.util.link_tree import MergeConflictError
 
@@ -178,7 +180,12 @@ def setup_parser(sp):
 
 
 def view(parser, args):
-    "Produce a view of a set of packages."
+    """Produce a view of a set of packages."""
+
+    if sys.platform == "win32" and args.action in ("hardlink", "hard"):
+        # Hard-linked views are not yet allowed on Windows.
+        # See https://github.com/spack/spack/pull/46335#discussion_r1757411915
+        tty.die("Hard linking is not supported on Windows. Please use symlinks or copy methods.")
 
     specs = spack.cmd.parse_specs(args.specs)
     path = args.path[0]

lib/spack/spack/filesystem_view.py

@@ -100,10 +100,12 @@ def view_copy(
 
         spack.relocate.relocate_text(files=[dst], prefixes=prefix_to_projection)
 
-    try:
-        os.chown(dst, src_stat.st_uid, src_stat.st_gid)
-    except OSError:
-        tty.debug(f"Can't change the permissions for {dst}")
+    # The os module on Windows does not have a chown function.
+    if sys.platform != "win32":
+        try:
+            os.chown(dst, src_stat.st_uid, src_stat.st_gid)
+        except OSError:
+            tty.debug(f"Can't change the permissions for {dst}")
 
 
 #: supported string values for `link_type` in an env, mapped to canonical values

lib/spack/spack/test/cmd/view.py

@@ -4,9 +4,12 @@
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
 import os.path
+import sys
 
 import pytest
 
+from llnl.util.symlink import _windows_can_symlink
+
 import spack.util.spack_yaml as s_yaml
 from spack.installer import PackageInstaller
 from spack.main import SpackCommand
@@ -16,7 +19,16 @@
 install = SpackCommand("install")
 view = SpackCommand("view")
 
-pytestmark = pytest.mark.not_on_windows("does not run on windows")
+if sys.platform == "win32":
+    if not _windows_can_symlink():
+        pytest.skip(
+            "Windows must be able to create symlinks to run tests.", allow_module_level=True
+        )
+    # TODO: Skipping hardlink command testing on windows until robust checks can be added.
+    #   See https://github.com/spack/spack/pull/46335#discussion_r1757411915
+    commands = ["symlink", "add", "copy", "relocate"]
+else:
+    commands = ["hardlink", "symlink", "hard", "add", "copy", "relocate"]
 
 
 def create_projection_file(tmpdir, projection):
@@ -28,7 +40,7 @@ def create_projection_file(tmpdir, projection):
     return projection_file
 
 
-@pytest.mark.parametrize("cmd", ["hardlink", "symlink", "hard", "add", "copy", "relocate"])
+@pytest.mark.parametrize("cmd", commands)
 def test_view_link_type(tmpdir, mock_packages, mock_archive, mock_fetch, install_mockery, cmd):
     install("libdwarf")
     viewpath = str(tmpdir.mkdir("view_{0}".format(cmd)))
@@ -41,7 +53,7 @@ def test_view_link_type(tmpdir, mock_packages, mock_archive, mock_fetch, install
     assert os.path.islink(package_prefix) == is_link_cmd
 
 
-@pytest.mark.parametrize("add_cmd", ["hardlink", "symlink", "hard", "add", "copy", "relocate"])
+@pytest.mark.parametrize("add_cmd", commands)
 def test_view_link_type_remove(
     tmpdir, mock_packages, mock_archive, mock_fetch, install_mockery, add_cmd
 ):
@@ -55,7 +67,7 @@ def test_view_link_type_remove(
     assert not os.path.exists(bindir)
 
 
-@pytest.mark.parametrize("cmd", ["hardlink", "symlink", "hard", "add", "copy", "relocate"])
+@pytest.mark.parametrize("cmd", commands)
 def test_view_projections(tmpdir, mock_packages, mock_archive, mock_fetch, install_mockery, cmd):
     install("libdwarf@20130207")