treemap: add more set tests

Author: thestinger

src/libstd/treemap.rs

@@ -1131,6 +1131,11 @@ mod test_set {
             check(a, b, expected, |x, y, z| x.intersection(y, z))
         }
 
+        check_intersection([], [], []);
+        check_intersection([1, 2, 3], [], []);
+        check_intersection([], [1, 2, 3], []);
+        check_intersection([2], [1, 2, 3], [2]);
+        check_intersection([1, 2, 3], [2], [2]);
         check_intersection([11, 1, 3, 77, 103, 5, -5],
                            [2, 11, 77, -9, -42, 5, 3],
                            [3, 5, 11, 77]);
@@ -1160,6 +1165,9 @@ mod test_set {
             check(a, b, expected, |x, y, z| x.symmetric_difference(y, z))
         }
 
+        check_symmetric_difference([], [], []);
+        check_symmetric_difference([1, 2, 3], [2], [1, 3]);
+        check_symmetric_difference([2], [1, 2, 3], [1, 3]);
         check_symmetric_difference([1, 3, 5, 9, 11],
                                    [-2, 3, 9, 14, 22],
                                    [-2, 1, 5, 11, 14, 22]);
@@ -1172,6 +1180,8 @@ mod test_set {
             check(a, b, expected, |x, y, z| x.union(y, z))
         }
 
+        check_union([], [], []);
+        check_union([1, 2, 3], [2], [1, 2, 3]);
         check_union([1, 3, 5, 9, 11, 16, 19, 24],
                     [-2, 1, 5, 9, 13, 19],
                     [-2, 1, 3, 5, 9, 11, 13, 16, 19, 24]);