`spack list`: add `--namesapce` / `--repo` option (#41948)

This adds options to `spack list` that allow you to list only packages from specific
repositories/namespaces, e.g.:

```console
spack list -r builtin
```

only lists packages from the `builtin` repo, while:

```console
spack list -r myrepo -r myrepo2
```

would list packages from `myrepo` and `myrepo2`, but not from `builtin`. Note that you
can use the same argument multiple times.

You can use either `-r` / `--repo` or `-N` / `--namespace`. `-N` is there to match the
corresponding option on `spack find`.

- [x] add `-r` / `--repo` / `-N` / `--namespace` argument
- [x] add test

2 files changed, 34 insertions, 1 deletions

diff --git a/lib/spack/spack/cmd/list.py b/lib/spack/spack/cmd/list.py
index 231e33dc51..eb34e38841 100644
--- a/lib/spack/spack/cmd/list.py
+++ b/lib/spack/spack/cmd/list.py
@@ -41,6 +41,16 @@ def setup_parser(subparser):
         help="optional case-insensitive glob patterns to filter results",
     )
     subparser.add_argument(
+        "-r",
+        "--repo",
+        "-N",
+        "--namespace",
+        dest="repos",
+        action="append",
+        default=[],
+        help="only list packages from the specified repo/namespace",
+    )
+    subparser.add_argument(
         "-d",
         "--search-description",
         action="store_true",
@@ -307,7 +317,11 @@ def list(parser, args):
     formatter = formatters[args.format]
 
     # Retrieve the names of all the packages
-    pkgs = set(spack.repo.all_package_names(args.virtuals))
+    repos = [spack.repo.PATH]
+    if args.repos:
+        repos = [spack.repo.PATH.get_repo(name) for name in args.repos]
+    pkgs = set().union(*[set(repo.all_package_names(args.virtuals)) for repo in repos])
+
     # Filter the set appropriately
     sorted_packages = filter_by_name(pkgs, args)
 
diff --git a/lib/spack/spack/test/cmd/list.py b/lib/spack/spack/test/cmd/list.py
index 848a6d20e4..a46e690cd2 100644
--- a/lib/spack/spack/test/cmd/list.py
+++ b/lib/spack/spack/test/cmd/list.py
@@ -3,6 +3,7 @@
 #
 # SPDX-License-Identifier: (Apache-2.0 OR MIT)
 
+import os.path
 import sys
 from textwrap import dedent
 
@@ -134,3 +135,21 @@ def test_list_count(mock_packages):
     assert int(output.strip()) == len(
         [name for name in spack.repo.all_package_names() if "py-" in name]
     )
+
+
+# def test_list_repos(mock_packages, builder_test_repository):
+def test_list_repos():
+    with spack.repo.use_repositories(
+        os.path.join(spack.paths.repos_path, "builtin.mock"),
+        os.path.join(spack.paths.repos_path, "builder.test"),
+    ):
+        total_pkgs = len(list().strip().split())
+
+        mock_pkgs = len(list("-r", "builtin.mock").strip().split())
+        builder_pkgs = len(list("-r", "builder.test").strip().split())
+
+        assert builder_pkgs == 8
+        assert total_pkgs > mock_pkgs > builder_pkgs
+
+        both_repos = len(list("-r", "builtin.mock", "-r", "builder.test").strip().split())
+        assert both_repos == total_pkgs