Fix unintended directory stripping during cylc install

CHANGES.md

@@ -46,6 +46,9 @@ in `global.cylc[install]source dirs`.
 
 ### Fixes
 
+[#4931](https://github.com/cylc/cylc-flow/pull/4931) - Fix cylc install for
+installing workflows from multi-level directories.
+
 [#4926](https://github.com/cylc/cylc-flow/pull/4926) - Fix a docstring
 formatting problem presenting in the UI mutation flow argument info.
 

cylc/flow/workflow_files.py

@@ -1564,7 +1564,7 @@ def install_workflow(
             Trying to install a workflow that is nested inside of another.
     """
     abort_if_flow_file_in_path(source)
-    source = Path(expand_path(source))
+    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)
@@ -1904,10 +1904,13 @@ def search_install_source_dirs(workflow_name: Union[Path, str]) -> Path:
 
 def get_source_workflow_name(source: Path) -> str:
     """Return workflow name relative to configured source dirs if possible,
-    else the basename of the given path."""
+    else the basename of the given path.
+    Note the source path provided should be fully expanded (user and env vars)
+    and normalised.
+    """
     for dir_ in get_source_dirs():
         try:
-            return str(source.relative_to(dir_))
+            return str(source.relative_to(Path(expand_path(dir_)).resolve()))
         except ValueError:
             continue
     return source.name

tests/functional/cylc-install/00-simple.t

@@ -18,7 +18,7 @@
 #------------------------------------------------------------------------------
 # Test workflow installation
 . "$(dirname "$0")/test_header"
-set_test_number 18
+set_test_number 22
 
 create_test_global_config "" "
 [install]
@@ -130,3 +130,25 @@ INSTALLED $RND_WORKFLOW_NAME/run2 from ${RND_WORKFLOW_SOURCE}
 __OUT__
 popd || exit 1
 purge_rnd_workflow
+
+# -----------------------------------------------------------------------------
+# Test running cylc install with multi level name works correctly
+TEST_NAME="${TEST_NAME_BASE}-install-multi-level"
+pushd cylc-src || exit 1
+make_rnd_workflow
+SUB_DIR="cylctb-x$(< /dev/urandom tr -dc _A-Z-a-z-0-9 | head -c6)"
+mkdir "${RND_WORKFLOW_NAME}/${SUB_DIR}"
+mv "${RND_WORKFLOW_NAME}/flow.cylc" "${RND_WORKFLOW_NAME}/${SUB_DIR}"
+
+run_ok "${TEST_NAME}" cylc install "${RND_WORKFLOW_NAME}/${SUB_DIR}"
+contains_ok "${TEST_NAME}.stdout" <<__OUT__
+INSTALLED ${RND_WORKFLOW_NAME}/${SUB_DIR}/run1 from ${RND_WORKFLOW_SOURCE}/$SUB_DIR
+__OUT__
+TEST_NAME="${TEST_NAME_BASE}-multi-level-from-pwd"
+pushd "${RND_WORKFLOW_SOURCE}/$SUB_DIR" || exit 1
+run_ok "${TEST_NAME}" cylc install
+contains_ok "${TEST_NAME}.stdout" <<__OUT__
+INSTALLED ${RND_WORKFLOW_NAME}/${SUB_DIR}/run2 from ${RND_WORKFLOW_SOURCE}/${SUB_DIR}
+__OUT__
+popd || exit 1
+purge_rnd_workflow

tests/unit/test_workflow_files.py

@@ -1526,9 +1526,9 @@ def test_search_install_source_dirs_empty(mock_glbl_cfg: Callable):
 @pytest.mark.parametrize(
     'path, expected',
     [
-        ('/isla/nublar/dennis/nedry', 'dennis/nedry'),
-        ('/isla/sorna/paul/kirby', 'paul/kirby'),
-        ('/mos/eisley/owen/skywalker', 'skywalker')
+        ('~/isla/nublar/dennis/nedry', 'dennis/nedry'),
+        ('~/isla/sorna/paul/kirby', 'paul/kirby'),
+        ('~/mos/eisley/owen/skywalker', 'skywalker')
     ]
 )
 def test_get_source_workflow_name(
@@ -1540,10 +1540,11 @@ def test_get_source_workflow_name(
         'cylc.flow.workflow_files.glbl_cfg',
         '''
         [install]
-            source dirs = /isla/nublar, /isla/sorna
+            source dirs = ~/isla/nublar, ${HOME}/isla/sorna
         '''
     )
-    assert get_source_workflow_name(Path(path)) == expected
+    assert get_source_workflow_name(
+        Path(path).expanduser().resolve()) == expected
 
 
 @pytest.mark.parametrize(