Merge branch 'feature/fix-almost-equal'

Author: srittau

NEWS.rst

@@ -6,9 +6,16 @@ API Additions
 
 * Add assert_not_almost_equal().
 
+Improvements
+------------
+
+* assert_almost_equal(): Raise ValueError if diff <= 0.
+
 Bug Fixes
 ---------
 
+* assert_almost_equal() would never fail if a delta was supplied and the
+  second number was smaller than the first.
 * Use fail() instead of raise AssertionError in a few assertions.
 
 News in asserts 0.7.2

asserts/__init__.py

@@ -167,12 +167,14 @@ def assert_almost_equal(first, second, places=None, msg=None, delta=None):
     AssertionError: 5 != 5.001 within 7 places
     >>> assert_almost_equal(5, 5.001, places=2)
     >>> assert_almost_equal(5, 5.001, delta=0.1)
-
     """
+
     if delta is not None and places is not None:
         raise TypeError("'places' and 'delta' are mutually exclusive")
     if delta is not None:
-        diff = second - first
+        if delta <= 0:
+            raise ValueError("delta must be larger than 0")
+        diff = abs(second - first)
         success = diff < delta
         detail_msg = "with delta={}".format(delta)
     else:
@@ -213,7 +215,9 @@ def assert_not_almost_equal(first, second, places=None, msg=None, delta=None):
     if delta is not None and places is not None:
         raise TypeError("'places' and 'delta' are mutually exclusive")
     if delta is not None:
-        diff = second - first
+        if delta <= 0:
+            raise ValueError("delta must be larger than 0")
+        diff = abs(second - first)
         success = diff >= delta
         detail_msg = "with delta={}".format(delta)
     else:

test_asserts.py

@@ -195,6 +195,9 @@ def test_assert_almost_equal__similar__places(self):
     def test_assert_almost_equal__similar__delta(self):
         assert_almost_equal(5, 5.001, delta=0.1)
 
+    def test_assert_almost_equal__similar__delta_reverse(self):
+        assert_almost_equal(5, 5.001, delta=0.1)
+
     def test_assert_almost_equal__not_similar__default_message(self):
         with _assert_raises_assertion("5 != 5.0001 within 7 places"):
             assert_almost_equal(5, 5.0001)
@@ -207,6 +210,10 @@ def test_assert_almost_equal__not_similar__delta__default_message(self):
         with _assert_raises_assertion("5 != 6 with delta=0.1"):
             assert_almost_equal(5, 6, delta=0.1)
 
+    def test_assert_almost_equal__not_similar__delta_reverse(self):
+        with _assert_raises_assertion("6 != 5 with delta=0.3"):
+            assert_almost_equal(6, 5, delta=0.3)
+
     def test_assert_almost_equal__not_similar__custom_message(self):
         with _assert_raises_assertion("test message"):
             assert_almost_equal(5, -5, msg="test message")
@@ -227,6 +234,22 @@ def test_assert_almost_equal__places_and_delta(self):
         else:
             raise AssertionError("TypeError not raised")
 
+    def test_assert_almost_equal__delta_eq_0(self):
+        try:
+            assert_almost_equal(5, 5, delta=0)
+        except ValueError:
+            pass
+        else:
+            raise AssertionError("ValueError not raised")
+
+    def test_assert_almost_equal__delta_lt_0(self):
+        try:
+            assert_almost_equal(5, 5, delta=-1)
+        except ValueError:
+            pass
+        else:
+            raise AssertionError("ValueError not raised")
+
     # assert_not_almost_equal()
 
     def test_assert_not_almost_equal__same(self):
@@ -245,9 +268,19 @@ def test_assert_not_almost_equal__similar__delta(self):
         with _assert_raises_assertion("5 == 5.1 with delta=0.1"):
             assert_not_almost_equal(5, 5.1, delta=0.1)
 
+    def test_assert_not_almost_equal__similar__delta_reverse(self):
+        with _assert_raises_assertion("5 != 6 with delta=0.3"):
+            assert_almost_equal(5, 6, delta=0.3)
+
     def test_assert_not_almost_equal__not_similar(self):
         assert_not_almost_equal(5, 5.0001)
 
+    def test_assert_not_almost_equal__not_similar__delta(self):
+        assert_not_almost_equal(5, 5.1, delta=0.05)
+
+    def test_assert_not_almost_equal__not_similar__delta_reverse(self):
+        assert_not_almost_equal(5.1, 5, delta=0.05)
+
     def test_assert_not_almost_equal__not_similar__custom_message(self):
         with _assert_raises_assertion("custom message"):
             assert_not_almost_equal(5, 5, msg="custom message")
@@ -268,6 +301,22 @@ def test_assert_not_almost_equal__places_and_delta(self):
         else:
             raise AssertionError("TypeError not raised")
 
+    def test_not_assert_almost_equal__delta_eq_0(self):
+        try:
+            assert_not_almost_equal(5, 5, delta=0)
+        except ValueError:
+            pass
+        else:
+            raise AssertionError("ValueError not raised")
+
+    def test_not_assert_almost_equal__delta_lt_0(self):
+        try:
+            assert_not_almost_equal(5, 5, delta=-1)
+        except ValueError:
+            pass
+        else:
+            raise AssertionError("ValueError not raised")
+
     # assert_less()
 
     def test_assert_less(self):