fix issue #4: raise specific HookCallError exception when arguments mismatch

Author: hpk42

CHANGELOG

@@ -1,3 +1,9 @@
+0.3.2
+-----
+
+- fix issue #4: specific HookCallError exception for when a hook call 
+  provides not enough arguments.
+
 0.3.1
 -----
 

pluggy.py

@@ -67,8 +67,9 @@
 import sys
 import inspect
 
-__version__ = '0.3.1'
-__all__ = ["PluginManager", "PluginValidationError",
+__version__ = '0.3.2'
+
+__all__ = ["PluginManager", "PluginValidationError", "HookCallError",
            "HookspecMarker", "HookimplMarker"]
 
 _py3 = sys.version_info > (3, 0)
@@ -590,7 +591,13 @@ def execute(self):
 
         while self.hook_impls:
             hook_impl = self.hook_impls.pop()
-            args = [all_kwargs[argname] for argname in hook_impl.argnames]
+            try:
+                args = [all_kwargs[argname] for argname in hook_impl.argnames]
+            except KeyError:
+                for argname in hook_impl.argnames:
+                    if argname not in all_kwargs:
+                        raise HookCallError(
+                            "hook call must provide argument %r" % (argname,))
             if hook_impl.hookwrapper:
                 return _wrapped_call(hook_impl.function(*args), self.execute)
             res = hook_impl.function(*args)
@@ -763,6 +770,10 @@ class PluginValidationError(Exception):
     """ plugin failed validation. """
 
 
+class HookCallError(Exception):
+    """ Hook was called wrongly. """
+
+
 if hasattr(inspect, 'signature'):
     def _formatdef(func):
         return "%s%s" % (

testing/test_pluggy.py

@@ -4,7 +4,7 @@
 import pytest
 
 from pluggy import (PluginManager, varnames, PluginValidationError,
-                    HookimplMarker, HookspecMarker)
+                    HookCallError, HookimplMarker, HookspecMarker)
 
 from pluggy import (_MultiCall, _TagTracer, HookImpl, _formatdef)
 
@@ -235,6 +235,22 @@ def he_method1(arg):
         l = pm.hook.he_method1.call_extra([he_method1], dict(arg=1))
         assert l == [10]
 
+    def test_call_with_too_few_args(self, pm):
+        class Hooks:
+            @hookspec
+            def he_method1(self, arg):
+                pass
+
+        pm.add_hookspecs(Hooks)
+
+        class Plugin1:
+            @hookimpl
+            def he_method1(self, arg):
+                0 / 0
+        pm.register(Plugin1())
+        with pytest.raises(HookCallError):
+            pm.hook.he_method1()
+
     def test_subset_hook_caller(self, pm):
         class Hooks:
             @hookspec
@@ -756,7 +772,7 @@ def test_tags_call_error(self):
         def f(x):
             return x
         multicall = self.MC([f], {})
-        pytest.raises(KeyError, multicall.execute)
+        pytest.raises(HookCallError, multicall.execute)
 
     def test_call_subexecute(self):
         @hookimpl
@@ -868,7 +884,7 @@ def m2():
 
 
 class TestHookRelay:
-    def test_hapmypath(self, pm):
+    def test_happypath(self, pm):
         class Api:
             @hookspec
             def hello(self, arg):