first succeeding precedence tests

test/test_evaluate/test_precedence.py

@@ -0,0 +1,13 @@
+from jedi.evaluate import precedence
+
+
+def test_simple():
+    p = precedence.create_precedence(iter([1, '+', 2]))
+    assert p.left == 1
+    assert p.operator == '+'
+    assert p.right == 2
+
+
+def test_invalid():
+    """Should just return a simple operation"""
+    assert precedence.create_precedence(iter([1, '+'])) == 1