Accept pathlib results from Python actions

CHANGES

@@ -13,6 +13,8 @@ Changes
 0.38.0 (*unreleased*)
 ======================
 
+- fix #195: accept pathlib paths returned by Python actions as successful
+  string results, including ``shutil.copy`` with a Path destination.
 - site/docs: landing page is now generated by sphinx (``doc/index.rst`` using ``sphinx-design``),
   replacing the hand-written ``doc/index.html`` and its vendored
   bootstrap / font-awesome / owl-carousel assets.

doc/tasks.rst

@@ -82,6 +82,7 @@ For **successful** completion it must return one of:
 * `None`
 * a dictionary
 * a string
+* a ``pathlib`` path (stored as its string representation)
 
 For **unsuccessful** completion it must return one of:
 
@@ -658,6 +659,8 @@ pathlib
 `doit` supports `pathlib <https://docs.python.org/3/library/pathlib.html>`_:
 file_dep, targets and CmdAction specified as a list can take as elements not
 only strings but also instances of any Path class from pathlib.
+Python actions may also return a pathlib path to indicate success; the result
+is saved as a string, just like a returned string.
 
 Lets take the compilation example and modify it to work with any number
 of header and source files in current directory using pathlib.

doc/uptodate.rst

@@ -38,6 +38,7 @@ time *doit* was executed.
 The "result" from the dependent task compared between different runs is given
 by its last action.
 The content for python-action is the value of the returned string or dict.
+Returned ``pathlib`` paths are stored as strings.
 For cmd-actions it is the output send to stdout plus stderr.
 
 `result_dep` also supports group-tasks. In this case it will check that the

doit/action.py

@@ -499,6 +499,8 @@ def execute(self, out=None, err=None):
             pass
         elif isinstance(returned_value, str):
             self.result = returned_value
+        elif isinstance(returned_value, PurePath):
+            self.result = str(returned_value)
         elif isinstance(returned_value, dict):
             self.values = returned_value
             self.result = returned_value
@@ -507,7 +509,8 @@ def execute(self, out=None, err=None):
         else:
             return TaskError("Python Task error: '%s'. It must return:\n"
                              "False for failed task.\n"
-                             "True, None, string or dict for successful task\n"
+                             "True, None, string, pathlib path or dict "
+                             "for successful task\n"
                              "returned %s (%s)" %
                              (self.py_callable, returned_value,
                               type(returned_value)))

tests/test_action.py

@@ -547,6 +547,24 @@ def success_sample():
         # nothing raised it was successful
         my_action.execute()
 
+    def test_success_path(self):
+        for result in (Path('output'), PurePath('output')):
+            with self.subTest(result=result):
+                my_action = action.PythonAction(lambda: result)
+                self.assertIsNone(my_action.execute())
+                self.assertEqual(str(result), my_action.result)
+                self.assertIsInstance(my_action.result, str)
+
+    def test_shutil_copy_path_result(self):
+        with tempfile.TemporaryDirectory() as folder:
+            source = Path(folder) / 'input.txt'
+            destination = Path(folder) / 'output.txt'
+            source.write_text('copied content')
+            my_action = action.PythonAction(shutil.copy, [source, destination])
+            self.assertIsNone(my_action.execute())
+            self.assertEqual('copied content', destination.read_text())
+            self.assertEqual(str(destination), my_action.result)
+
     def test_success_dict(self):
         def success_sample():
             return {}