a new plugin for asserting that warnings have been shown to a user.

--HG--
branch : trunk

py/test/defaultconftest.py

@@ -10,5 +10,5 @@ Generator = py.test.collect.Generator
 Function = py.test.collect.Function
 Instance = py.test.collect.Instance
 
-pytest_plugins = "default terminal xfail tmpdir execnetcleanup monkeypatch pdb".split()
+pytest_plugins = "default terminal xfail tmpdir execnetcleanup monkeypatch recwarn pdb".split()
 

py/test/plugin/pytest_recwarn.py

@@ -0,0 +1,94 @@
+"""
+
+"recwarn" funcarg plugin that helps to assert 
+that warnings are shown to a user.  See the test
+at the bottom for an example. 
+
+"""
+import py
+import os
+
+class RecwarnPlugin:
+    def pytest_funcarg__recwarn(self, request):
+        """ check that warnings have been raised. """ 
+        warnings = WarningsRecorder()
+        request.addfinalizer(warnings.finalize)
+        return warnings
+
+class RecordedWarning:
+    def __init__(self, message, category, filename, lineno, line):
+        self.message = message
+        self.category = category
+        self.filename = filename
+        self.lineno = lineno
+        self.line = line
+
+class WarningsRecorder:
+    def __init__(self):
+        warningmodule = py.std.warnings
+        self.list = []
+        def showwarning(message, category, filename, lineno, line=0):
+            self.list.append(RecordedWarning(
+                message, category, filename, lineno, line))
+            try:
+                self.old_showwarning(message, category, 
+                    filename, lineno, line=line)
+            except TypeError:
+                # < python2.6 
+                self.old_showwarning(message, category, filename, lineno)
+        self.old_showwarning = warningmodule.showwarning
+        warningmodule.showwarning = showwarning
+
+    def pop(self, cls=Warning):
+        """ pop the first recorded warning, raise exception if not exists."""
+        for i, w in py.builtin.enumerate(self.list):
+            if issubclass(w.category, cls):
+                return self.list.pop(i)
+        assert 0, "%r not found in %r" %(cls, self.list)
+
+    #def resetregistry(self):
+    #    import warnings
+    #    warnings.onceregistry.clear()
+    #    warnings.__warningregistry__.clear()
+
+    def reset(self): 
+        self.list[:] = []
+
+    def finalize(self):
+        py.std.warnings.showwarning = self.old_showwarning
+
+def test_WarningRecorder():
+    showwarning = py.std.warnings.showwarning
+    rec = WarningsRecorder()
+    assert py.std.warnings.showwarning != showwarning
+    assert not rec.list
+    py.std.warnings.warn_explicit("hello", UserWarning, "xyz", 13)
+    assert len(rec.list) == 1
+    py.std.warnings.warn(DeprecationWarning("hello"))
+    assert len(rec.list) == 2
+    warn = rec.pop()
+    assert str(warn.message) == "hello"
+    l = rec.list
+    rec.reset()
+    assert len(rec.list) == 0
+    assert l is rec.list
+    py.test.raises(AssertionError, "rec.pop()")
+    rec.finalize()
+    assert showwarning == py.std.warnings.showwarning
+
+def test_recwarn_functional(testdir):
+    sorter = testdir.inline_runsource("""
+        pytest_plugins = 'pytest_recwarn', 
+        import warnings
+        oldwarn = warnings.showwarning
+        def test_method(recwarn):
+            assert warnings.showwarning != oldwarn
+            warnings.warn("hello")
+            warn = recwarn.pop()
+            assert isinstance(warn.message, UserWarning)
+        def test_finalized():
+            assert warnings.showwarning == oldwarn
+    """)
+    res = sorter.countoutcomes()
+    assert tuple(res) == (2, 0, 0), res
+        

py/test/testing/test_collect.py

@@ -131,9 +131,10 @@ class TestCollectFS:
         names = [x.name for x in col.collect()]
         assert names == ["dir1", "dir2", "test_one.py", "test_two.py", "x"]
 
-    def test_collector_deprecated_run_method(self, testdir):
+    def test_collector_deprecated_run_method(self, testdir, recwarn):
         modcol = testdir.getmodulecol("pass")
-        res1 = py.test.deprecated_call(modcol.run)
+        res1 = modcol.run()
+        recwarn.pop(DeprecationWarning) 
         res2 = modcol.collect()
         assert res1 == [x.name for x in res2]