Preserve defaults for positional-only parameters

fire/core_test.py

@@ -24,6 +24,18 @@
 
 class CoreTest(testutils.BaseTestCase):
 
+  def testBuiltinPositionalOnlyDefault(self):
+    with self.assertOutputMatches(stdout='   hi', stderr=None):
+      self.assertEqual(core.Fire('hi'.rjust, command=['5']), '   hi')
+
+  def testBuiltinPositionalOnlyDefaultOverride(self):
+    with self.assertOutputMatches(stdout='___hi', stderr=None):
+      self.assertEqual(core.Fire('hi'.rjust, command=['5', '_']), '___hi')
+
+  def testBuiltinPositionalOnlyRequiredArgument(self):
+    with self.assertRaisesFireExit(2, 'required argument: width'):
+      core.Fire('hi'.rjust, command=[])
+
   def testOneLineResult(self):
     self.assertEqual(core._OneLineResult(1), '1')  # pylint: disable=protected-access
     self.assertEqual(core._OneLineResult('hello'), 'hello')  # pylint: disable=protected-access

fire/inspectutils.py

@@ -128,9 +128,10 @@ def Py3GetFullArgSpec(fn):
     name = param.name
 
     # pylint: disable=protected-access
-    if kind is inspect._POSITIONAL_ONLY:  # type: ignore
-      args.append(name)
-    elif kind is inspect._POSITIONAL_OR_KEYWORD:  # type: ignore
+    if kind in (
+        inspect._POSITIONAL_ONLY,
+        inspect._POSITIONAL_OR_KEYWORD,
+    ):  # type: ignore
       args.append(name)
       if param.default is not param.empty:
         defaults += (param.default,)

fire/inspectutils_test.py

@@ -14,6 +14,7 @@
 
 """Tests for the inspectutils module."""
 
+import inspect
 import os
 
 from fire import inspectutils
@@ -52,6 +53,35 @@ def testGetFullArgSpecFromBuiltin(self):
     self.assertEqual(spec.kwonlydefaults, {})
     self.assertEqual(spec.annotations, {})
 
+  def testGetFullArgSpecPositionalOnlyDefault(self):
+    spec = inspectutils.GetFullArgSpec(dict.get)
+    self.assertEqual(spec.args, ['self', 'key', 'default'])
+    self.assertEqual(spec.defaults, (None,))
+
+  def testGetFullArgSpecBoundPositionalOnlyDefault(self):
+    spec = inspectutils.GetFullArgSpec({}.get)
+    self.assertEqual(spec.args, ['key', 'default'])
+    self.assertEqual(spec.defaults, (None,))
+
+  def testGetFullArgSpecMixedPositionalDefaults(self):
+    def function(*args, **kwargs):
+      del args, kwargs
+
+    # Use a signature object so this test also parses on Python 3.7.
+    function.__signature__ = inspect.Signature([
+        inspect.Parameter('required', inspect.Parameter.POSITIONAL_ONLY),
+        inspect.Parameter('first', inspect.Parameter.POSITIONAL_ONLY,
+                          default=1),
+        inspect.Parameter('second', inspect.Parameter.POSITIONAL_OR_KEYWORD,
+                          default=2),
+        inspect.Parameter('third', inspect.Parameter.KEYWORD_ONLY, default=3),
+    ])
+    spec = inspectutils.GetFullArgSpec(function)
+    self.assertEqual(spec.args, ['required', 'first', 'second'])
+    self.assertEqual(spec.defaults, (1, 2))
+    self.assertEqual(spec.kwonlyargs, ['third'])
+    self.assertEqual(spec.kwonlydefaults, {'third': 3})
+
   def testGetFullArgSpecFromSlotWrapper(self):
     spec = inspectutils.GetFullArgSpec(tc.NoDefaults)
     self.assertEqual(spec.args, [])