bites 212 - Use contextlib.suppress to suppress exceptions as opposed to a try/catch method

Author: boraxpr

.gitignore

@@ -78,3 +78,4 @@
 /81/README.md
 /234/README.md
 /219/README.md
+/212/README.md

212/summing.py

@@ -0,0 +1,16 @@
+from contextlib import suppress
+
+
+def sum_numbers(numbers):
+    """This generator divides each nummber by its consecutive number.
+       So if it gets passed in [4, 2, 1] it yields 4/2 and 2/1.
+       It ignores ZeroDivisionError and TypeError exceptions (latter happens
+       when a string or other non-numeric data type is in numbers)
+
+       Task: use contextlib's suppress twice to make the code below more concise.
+    """
+    for i, j in zip(numbers, numbers[1:]):
+        # replace the block below
+        with suppress(TypeError):
+            with suppress(ZeroDivisionError):
+                yield i/j

212/test_summing.py

@@ -0,0 +1,21 @@
+import inspect
+
+from summing import sum_numbers
+
+
+def test_functionality():
+    numbers = [1, 2, 0, 4, 5, 12, 'a', 3]
+    actual = list(sum_numbers(numbers))
+    expected = [0.5, 0.0, 0.8, 0.4166666666666667]
+    assert actual == expected
+
+
+def test_use_of_idioms():
+    src = inspect.getsource(sum_numbers)
+    assert 'try' not in src
+    assert 'except ' not in src
+    assert 'yield' in src
+    assert 'TypeError' in src
+    assert 'ZeroDivisionError' in src
+    assert src.count('suppress(') in (1, 2)
+    assert src.count('with') in (1, 2)