reduced errors when generating function call instances

pytest/test_function_call.py

@@ -0,0 +1,48 @@
+# std
+import string
+# 3rd party
+from hypothesis import strategies as st
+from hypothesis import given, assume
+# uncompyle
+from validate import validate_uncompyle
+
+
+alpha = st.sampled_from(string.ascii_lowercase)
+numbers = st.sampled_from(string.digits)
+alphanum = st.sampled_from(string.ascii_lowercase + string.digits)
+expressions = st.sampled_from([x for x in string.ascii_lowercase + string.digits] + ['x+1'])
+
+
+@st.composite
+def function_calls(draw):
+    """
+    Strategy factory for generating function calls.
+
+    :param draw: Callable which draws examples from other strategies.
+
+    :return: The function call text.
+    """
+    positional_args = draw(st.lists(alphanum, min_size=0, max_size=3))
+    named_args = [x + '=0' for x in draw(st.lists(alpha, min_size=0, max_size=3))]
+    star_args = ['*' + x for x in draw(st.lists(alpha, min_size=0, max_size=1))]
+    double_star_args = ['**' + x for x in draw(st.lists(alpha, min_size=0, max_size=1))]
+
+    arguments = positional_args + named_args + star_args + double_star_args
+    draw(st.randoms()).shuffle(arguments)
+    arguments = ','.join(arguments)
+
+    function_call = 'fn({arguments})'.format(arguments=arguments)
+    try:
+        # TODO: Figure out the exact rules for ordering of positional named,
+        # star args and double star args and in which versions the various
+        # types of arguments are supported so we don't need to check that the
+        # expression compiles like this.
+        compile(function_call, '<string>', 'single')
+    except:
+        assume(False)
+    return function_call
+
+
+@given(function_calls())
+def test_function_call(function_call):
+    validate_uncompyle(function_call)