Check run name as well as workflow name in Cylc install

Update changes.d/6264.fix.md

Co-authored-by: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>

Apply suggestions from code review

Co-authored-by: Ronnie Dutta <61982285+MetRonnie@users.noreply.github.com>

Restore workflow_files

changes.d/6264.fix.md

@@ -0,0 +1 @@
+Fix bug where `cylc install` failed to prevent invalid run names.

cylc/flow/install.py

@@ -285,13 +285,18 @@ def install_workflow(
     source = Path(expand_path(source)).resolve()
     if not workflow_name:
         workflow_name = get_source_workflow_name(source)
-    validate_workflow_name(workflow_name, check_reserved_names=True)
     if run_name is not None:
+        validate_workflow_name(
+            os.path.join(workflow_name, run_name),
+            being_validated='workflow and run'
+        )
         if len(Path(run_name).parts) != 1:
             raise WorkflowFilesError(
                 f'Run name cannot be a path. (You used {run_name})'
             )
         check_reserved_dir_names(run_name)
+    else:
+        validate_workflow_name(workflow_name, check_reserved_names=True)
     validate_source_dir(source, workflow_name)
     run_path_base = Path(get_workflow_run_dir(workflow_name))
     relink, run_num, rundir = get_run_dir_info(

tests/unit/test_install.py

@@ -542,3 +542,19 @@ def test_validate_source_dir(tmp_run_dir: Callable, tmp_src_dir: Callable):
     with pytest.raises(WorkflowFilesError) as exc_info:
         validate_source_dir(src_dir, 'ajay')
     assert "exists in source directory" in str(exc_info.value)
+
+
+def test_install_workflow_failif_bad_name(tmp_src_dir):
+    """If a run_name is given validate_workflow_name is called on
+    the workflow and the run name in combination.
+    """
+    src_dir: Path = tmp_src_dir('ludlow')
+    # It only has a workflow name:
+    with pytest.raises(WorkflowFilesError, match='can only contain'):
+        install_workflow(src_dir, workflow_name='foo?')
+    # It only has a run name:
+    with pytest.raises(WorkflowFilesError, match='can only contain'):
+        install_workflow(src_dir, run_name='foo?')
+    # It has a legal workflow name, but an invalid run name:
+    with pytest.raises(WorkflowFilesError, match='can only contain'):
+        install_workflow(src_dir, workflow_name='foo', run_name='bar?')