Treat python_app input/output default arguments like other magic keywords, and like bash_app

parsl/app/app.py

@@ -66,6 +66,10 @@ def __init__(self, func: Callable,
             self.kwargs['walltime'] = params['walltime'].default
         if 'parsl_resource_specification' in params:
             self.kwargs['parsl_resource_specification'] = params['parsl_resource_specification'].default
+        if 'outputs' in params:
+            self.kwargs['outputs'] = params['outputs'].default
+        if 'inputs' in params:
+            self.kwargs['inputs'] = params['inputs'].default
 
     @abstractmethod
     def __call__(self, *args: Any, **kwargs: Any) -> AppFuture:

parsl/tests/test_bash_apps/test_inputs_default.py

@@ -0,0 +1,25 @@
+import pytest
+
+from parsl import AUTO_LOGNAME, Config, bash_app, python_app
+from parsl.executors import ThreadPoolExecutor
+
+
+def local_config():
+    return Config(executors=[ThreadPoolExecutor()])
+
+
+@pytest.mark.local
+def test_default_inputs():
+    @python_app
+    def identity(inp):
+        return inp
+
+    @bash_app
+    def sum_inputs(inputs=[identity(1), identity(2)], stdout=AUTO_LOGNAME):
+        calc = sum(inputs)
+        return f"echo {calc}"
+
+    fut = sum_inputs()
+    fut.result()
+    with open(fut.stdout, 'r') as f:
+        assert int(f.read()) == 3

parsl/tests/test_python_apps/test_inputs_default.py

@@ -0,0 +1,22 @@
+import pytest
+
+import parsl
+from parsl import python_app
+from parsl.executors.threads import ThreadPoolExecutor
+
+
+def local_config():
+    return parsl.Config(executors=[ThreadPoolExecutor()])
+
+
+@pytest.mark.local
+def test_default_inputs():
+    @python_app
+    def identity(inp):
+        return inp
+
+    @python_app
+    def add_inputs(inputs=[identity(1), identity(2)]):
+        return sum(inputs)
+
+    assert add_inputs().result() == 3