warn if instances are callable and have a test name

_pytest/python.py

@@ -11,7 +11,8 @@ cutdir = py.path.local(_pytest.__file__).dirpath()
 
 NoneType = type(None)
 NOTSET = object()
-
+isfunction = inspect.isfunction
+isclass = inspect.isclass
 callable = py.builtin.callable
 
 def getfslineno(obj):
@@ -44,7 +45,7 @@ class FixtureFunctionMarker:
         self.ids = ids
 
     def __call__(self, function):
-        if inspect.isclass(function):
+        if isclass(function):
             raise ValueError(
                     "class fixtures not supported (may be in the future)")
         function._pytestfixturefunction = self
@@ -213,14 +214,19 @@ def pytest_pycollect_makeitem(__multicall__, collector, name, obj):
     res = __multicall__.execute()
     if res is not None:
         return res
-    if inspect.isclass(obj):
+    if isclass(obj):
         #if hasattr(collector.obj, 'unittest'):
         #    return # we assume it's a mixin class for a TestCase derived one
         if collector.classnamefilter(name):
             Class = collector._getcustomclass("Class")
             return Class(name, parent=collector)
-    elif collector.funcnamefilter(name) and hasattr(obj, '__call__') and \
+    elif collector.funcnamefilter(name) and hasattr(obj, "__call__") and \
         getfixturemarker(obj) is None:
+        if not isfunction(obj):
+            collector.warn(code="C2", message=
+                "cannot collect %r because it is not a function."
+                % name, )
+            return
         if is_generator(obj):
             return Generator(name, parent=collector)
         else:
@@ -498,10 +504,9 @@ class Class(PyCollector):
     """ Collector for test methods. """
     def collect(self):
         if hasinit(self.obj):
-            pytest.skip("class %s.%s with __init__ won't get collected" % (
-                self.obj.__module__,
-                self.obj.__name__,
-            ))
+            self.warn("C1", "cannot collect test class %r because it has a "
+                "__init__ constructor" % self.obj.__name__)
+            return []
         return [self._getcustomclass("Instance")(name="()", parent=self)]
 
     def setup(self):

_pytest/terminal.py

@@ -15,7 +15,7 @@ def pytest_addoption(parser):
     group._addoption('-r',
          action="store", dest="reportchars", default=None, metavar="chars",
          help="show extra test summary info as specified by chars (f)ailed, "
-              "(E)error, (s)skipped, (x)failed, (X)passed.")
+              "(E)error, (s)skipped, (x)failed, (X)passed (w)warnings.")
     group._addoption('-l', '--showlocals',
          action="store_true", dest="showlocals", default=False,
          help="show locals in tracebacks (disabled by default).")

testing/python/collect.py

@@ -33,8 +33,8 @@ class TestModule:
         pytest.raises(ImportError, lambda: modcol.obj)
 
 class TestClass:
-    def test_class_with_init_skip_collect(self, testdir):
-        modcol = testdir.getmodulecol("""
+    def test_class_with_init_warning(self, testdir):
+        testdir.makepyfile("""
             class TestClass1:
                 def __init__(self):
                     pass
@@ -42,11 +42,11 @@ class TestClass:
                 def __init__(self):
                     pass
         """)
-        l = modcol.collect()
-        assert len(l) == 2
-
-        for classcol in l:
-            pytest.raises(pytest.skip.Exception, classcol.collect)
+        result = testdir.runpytest("-rw")
+        result.stdout.fnmatch_lines("""
+            WC1*test_class_with_init_warning.py*__init__*
+            *2 warnings*
+        """)
 
     def test_class_subclassobject(self, testdir):
         testdir.getmodulecol("""
@@ -276,6 +276,17 @@ class TestFunction:
         assert isinstance(modcol, pytest.Module)
         assert hasattr(modcol.obj, 'test_func')
 
+    def test_function_as_object_instance_ignored(self, testdir):
+        item = testdir.makepyfile("""
+            class A:
+                def __call__(self, tmpdir):
+                    0/0
+
+            test_a = A()
+        """)
+        reprec = testdir.inline_run()
+        reprec.assertoutcome()
+
     def test_function_equality(self, testdir, tmpdir):
         from _pytest.python import FixtureManager
         config = testdir.parseconfigure()