Merge pull request #526 from palaviv/assertRaises

windelbouwman · web-flow · commit c675a59288b8 · 2019-02-23T13:35:19.000+01:00
Add assertRaises context manager to testutils
diff --git a/tests/snippets/set.py b/tests/snippets/set.py
@@ -1,4 +1,4 @@
-from testutils import assert_raises
+from testutils import assert_raises, assertRaises
 
 assert set([1,2]) == set([1,2])
 assert not set([1,2,3]) == set([1,2])
@@ -109,12 +109,8 @@ def __hash__(self):
 a = set([1,2,3])
 a |= set([3,4,5])
 assert a == set([1,2,3,4,5])
-try:
+with assertRaises(TypeError):
 	a |= 1
-except TypeError:
-	pass
-else:
-	assert False, "TypeError not raised"
 
 a = set([1,2,3])
 a.intersection_update([2,3,4,5])
@@ -124,12 +120,8 @@ def __hash__(self):
 a = set([1,2,3])
 a &= set([2,3,4,5])
 assert a == set([2,3])
-try:
+with assertRaises(TypeError):
 	a &= 1
-except TypeError:
-	pass
-else:
-	assert False, "TypeError not raised"
 
 a = set([1,2,3])
 a.difference_update([3,4,5])
@@ -139,12 +131,8 @@ def __hash__(self):
 a = set([1,2,3])
 a -= set([3,4,5])
 assert a == set([1,2])
-try:
+with assertRaises(TypeError):
 	a -= 1
-except TypeError:
-	pass
-else:
-	assert False, "TypeError not raised"
 
 a = set([1,2,3])
 a.symmetric_difference_update([3,4,5])
@@ -154,9 +142,5 @@ def __hash__(self):
 a = set([1,2,3])
 a ^= set([3,4,5])
 assert a == set([1,2,4,5])
-try:
+with assertRaises(TypeError):
 	a ^= 1
-except TypeError:
-	pass
-else:
-	assert False, "TypeError not raised"
diff --git a/tests/snippets/testutils.py b/tests/snippets/testutils.py
@@ -18,3 +18,19 @@ def assert_raises(exc_type, expr, msg=None):
         if msg is not None:
             failmsg += ': {!s}'.format(msg)
         assert False, failmsg
+
+
+class assertRaises:
+    def __init__(self, expected):
+        self.expected = expected
+
+    def __enter__(self):
+        return self
+
+    def __exit__(self, exc_type, exc_val, exc_tb):
+        if exc_type is None:
+            failmsg = '{!s} was not raised'.format(self.expected.__name_)
+            assert False, failmsg            
+        if not issubclass(exc_type, self.expected):
+            return False
+        return True
