DM-26144 Inherit configs when inheriting a Pipeline

python/lsst/pipe/base/pipeline.py

@@ -33,6 +33,7 @@
 from typing import Mapping, Union, Generator, TYPE_CHECKING
 
 import copy
+import os
 
 # -----------------------------
 #  Imports for other modules --
@@ -335,7 +336,7 @@ def toExpandedPipeline(self) -> Generator[TaskDef]:
                     if configIR.dataId is None:
                         if configIR.file:
                             for configFile in configIR.file:
-                                overrides.addFileOverride(configFile)
+                                overrides.addFileOverride(os.path.expandvars(configFile))
                         if configIR.python is not None:
                             overrides.addPythonOverride(configIR.python)
                         for key, value in configIR.rest.items():

python/lsst/pipe/base/pipelineIR.py

@@ -380,7 +380,18 @@ def process_args(argument: Union[str, dict]) -> dict:
                                  "be unique")
             accumulate_tasks.update(tmp_IR.tasks)
             self.contracts.extend(tmp_IR.contracts)
-        accumulate_tasks.update(self.tasks)
+
+        # merge the dict of label:TaskIR objects, preserving any configs in the
+        # imported pipeline if the labels point to the same class
+        for label, task in self.tasks.items():
+            if label not in accumulate_tasks:
+                accumulate_tasks[label] = task
+            elif accumulate_tasks[label].klass == task.klass:
+                if task.config is not None:
+                    for config in task.config:
+                        accumulate_tasks[label].add_or_update_config(config)
+            else:
+                accumulate_tasks[label] = task
         self.tasks = accumulate_tasks
 
     def _read_tasks(self, loaded_yaml):

tests/testPipeline2.yaml

@@ -1,3 +1,6 @@
 description: Test Pipeline
 tasks:
-  modA: "test.moduleA"
+  modA:
+      class: "test.moduleA"
+      config:
+          value1: 1

tests/test_pipelineIR.py

@@ -191,6 +191,36 @@ def testInheritParsing(self):
         pipeline = PipelineIR.from_string(pipeline_str)
         self.assertEqual(pipeline.contracts, [])
 
+        # Test that configs are inherited when defining the same task again with
+        # the same label
+        pipeline_str = textwrap.dedent("""
+        description: Test Pipeline
+        inherits:
+            - $PIPE_BASE_DIR/tests/testPipeline2.yaml
+        tasks:
+          modA:
+            class: "test.moduleA"
+            config:
+                value2: 2
+        """)
+        pipeline = PipelineIR.from_string(pipeline_str)
+        self.assertEqual(pipeline.tasks["modA"].config[0].rest, {"value1": 1, "value2": 2})
+
+        # Test that configs are not inherited when redefining the task
+        # associated with a label
+        pipeline_str = textwrap.dedent("""
+        description: Test Pipeline
+        inherits:
+            - $PIPE_BASE_DIR/tests/testPipeline2.yaml
+        tasks:
+          modA:
+            class: "test.moduleAReplace"
+            config:
+                value2: 2
+        """)
+        pipeline = PipelineIR.from_string(pipeline_str)
+        self.assertEqual(pipeline.tasks["modA"].config[0].rest, {"value2": 2})
+
     def testReadContracts(self):
         # Verify that contracts are read in from a pipeline
         location = os.path.expandvars("$PIPE_BASE_DIR/tests/testPipeline1.yaml")