1 files changed, 54 insertions, 8 deletions
diff --git a/src/03/avl_tree_test.c b/src/03/avl_tree_test.c
index 3f7a0e8..ccfcefb 100644
--- a/src/03/avl_tree_test.c
+++ b/src/03/avl_tree_test.c
@@ -28,6 +28,15 @@ Ensure(insert_changes_height) {
   assert_that(tree->left->height, is_equal_to(1));
 }
 
+Ensure(insert_creates_a_new_root) {
+  AVLTree *tree = avl_tree_insert(NULL, 10);
+
+  assert_that(tree, is_not_equal_to(NULL));
+  assert_that(tree->value, is_equal_to(10));
+  assert_that(tree->left, is_equal_to(NULL));
+  assert_that(tree->right, is_equal_to(NULL));
+}
+
 Ensure(insert_performs_a_left_rotation) {
 /*
   (10)                  (20)
@@ -62,15 +71,52 @@ Ensure(insert_performs_a_right_rotation) {
   assert_that(tree->right->value, is_equal_to(30));
 }
 
+Ensure(insert_performs_a_left_right_rotation) {
+/*
+   (30)         (20)
+   /           /    \
+(10)     -> (10)    (30)
+   \
+   (20)
+*/
+  AVLTree *tree = avl_tree_initialize(30);
+  tree = avl_tree_insert(tree, 10);
+  tree = avl_tree_insert(tree, 20);
+
+  assert_that(tree->value, is_equal_to(20));
+  assert_that(tree->left->value, is_equal_to(10));
+  assert_that(tree->right->value, is_equal_to(30));
+}
+
+Ensure(insert_performs_a_right_left_rotation) {
+/*
+(10)             (20)
+    \            /  \
+    (30)  --> (10)  (30)
+   /
+ (20)
+*/
+  AVLTree *tree = avl_tree_initialize(10);
+  tree = avl_tree_insert(tree, 30);
+  tree = avl_tree_insert(tree, 20);
+
+  assert_that(tree->value, is_equal_to(20));
+  assert_that(tree->left->value, is_equal_to(10));
+  assert_that(tree->right->value, is_equal_to(30));
+}
+
 TestSuite *avl_tree_tests() {
-  TestSuite *suite = create_test_suite();
-  add_test(suite, initialize_returns_new_tree);
-  add_test(suite, size_returns_zero);
-  add_test(suite, insert_changes_size);
-  add_test(suite, insert_changes_height);
-  add_test(suite, insert_performs_a_left_rotation);
-  add_test(suite, insert_performs_a_right_rotation);
-  return suite;
+  TestSuite *x = create_test_suite();
+  add_test(x, initialize_returns_new_tree);
+  add_test(x, size_returns_zero);
+  add_test(x, insert_changes_size);
+  add_test(x, insert_changes_height);
+  add_test(x, insert_creates_a_new_root);
+  add_test(x, insert_performs_a_left_rotation);
+  add_test(x, insert_performs_a_right_rotation);
+  add_test(x, insert_performs_a_left_right_rotation);
+  add_test(x, insert_performs_a_right_left_rotation);
+  return x;
 }
 
 int main(int argc, char **argv) {