Test that no repr() can slow down completion.

Was reported with issue #919.

test/test_speed.py

@@ -51,3 +51,19 @@ class TestSpeed(TestCase):
         with open('speed/precedence.py') as f:
             line = len(f.read().splitlines())
         assert jedi.Script(line=line, path='speed/precedence.py').goto_definitions()
+
+    @_check_speed(0.1)
+    def test_no_repr_computation(self):
+        """
+        For Interpreter completion aquisition of sourcefile can trigger
+        unwanted computation of repr(). Exemple : big pandas data.
+        See issue #919.
+        """
+        class Slow_repr():
+            "class to test what happens if __repr__ is very slow."
+            def some_method(self):
+                pass
+            def __repr__(self):
+                time.sleep(0.2)
+        test = Slow_repr()
+        jedi.Interpreter('test.som', [locals()]).completions()