add (probably bad) way to handle nested references

scuba/config.py

@@ -382,6 +382,16 @@ def _process_reference(doc: dict, key: Reference) -> Any:
             cur = cur[k]
     except KeyError:
         raise yaml.YAMLError(f"Key {key!r} not found")
+    if isinstance(cur, list):
+            new_cur = []
+            for c in cur:
+                if isinstance(c, Reference):
+                    # use += to concatenate list type
+                    new_cur += _process_reference(doc, c)
+                else:
+                    # use append to concatenate other types
+                    new_cur.append(c)
+            cur = new_cur
     return cur
 
 

tests/test_config.py

@@ -342,10 +342,73 @@ def test_load_config_from_gitlab_reference_script_list(self) -> None:
               important: !from_gitlab {GITLAB_YML} build.script
             """
         )
-        assert config.image == "bosybux"
-        assert len(config.aliases) == 1
         assert config.aliases["important"].script == ["do-something-really-important", "depends-on-important-stuff"]
 
+
+    def test_load_config_from_gitlab_nested_reference(self) -> None:
+        """load a .gitlab-ci.yml with !reference in script"""
+        GITLAB_YML.write_text(
+            """
+            .initial:
+              script:
+                - the-most-important-thing
+
+            .setup:
+              script:
+                - !reference [.initial, script]
+                - do-something-really-important
+
+            build:
+              stage: build
+              script:
+                - !reference [.setup, script]
+                - depends-on-important-stuff
+            """
+        )
+        config = load_config(
+            config_text=f"""
+            image: bosybux
+            aliases:
+              important: !from_gitlab {GITLAB_YML} build.script
+            """
+        )
+        assert config.aliases["important"].script == ["the-most-important-thing", "do-something-really-important", "depends-on-important-stuff"]
+
+    def test_load_config_from_gitlab_double_nested_reference(self) -> None:
+        """load a .gitlab-ci.yml with !reference in script"""
+        GITLAB_YML.write_text(
+            """
+            .preinit:
+              script:
+                - the-utmost-importance
+
+            .initial:
+              script:
+                - !reference [.preinit, script]
+                - the-most-important-thing
+
+            .setup:
+              script:
+                - !reference [.initial, script]
+                - do-something-really-important
+
+            build:
+              stage: build
+              script:
+                - !reference [.setup, script]
+                - depends-on-important-stuff
+            """
+        )
+        config = load_config(
+            config_text=f"""
+            image: bosybux
+            aliases:
+              important: !from_gitlab {GITLAB_YML} build.script
+            """
+        )
+        assert config.aliases["important"].script == ["the-utmost-importance","the-most-important-thing", "do-something-really-important", "depends-on-important-stuff"]
+
+
     def test_load_config_from_gitlab_with_bad_reference(self) -> None:
         """load_config loads a config using !from_gitlab with !reference tag"""
         GITLAB_YML.write_text(