diff --git a/src/arraylist.c b/src/arraylist.c
index 494467d..7eeb568 100644
--- a/src/arraylist.c
+++ b/src/arraylist.c
@@ -89,7 +89,7 @@ bool arraylist_is_empty(const ArrayList *arr) {
     if (arr == NULL) {
         return true;
     }
-    return arr->capacity == 0;
+    return arr->len == 0;
 }
 
 static ArrayListErr arraylist_grow(ArrayList *arr) {
diff --git a/test/test_arraylist.c b/test/test_arraylist.c
index a136489..a09ebad 100644
--- a/test/test_arraylist.c
+++ b/test/test_arraylist.c
@@ -9,11 +9,13 @@
 
 #include "arraylist.h"
 
+// INIT
+
 static void test_init_valid_parameters(void **state) {
     (void) state;
 
     ArrayList *arr = arraylist_init(64, sizeof(int));
-    assert_ptr_not_equal(arr, NULL);
+    assert_non_null(arr);
     arraylist_destroy(&arr);
 }
 
@@ -21,7 +23,7 @@ static void test_init_zero_capacity(void **state) {
     (void) state;
 
     ArrayList *arr = arraylist_init(0, sizeof(int));
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
     arraylist_destroy(&arr);
 }
 
@@ -29,7 +31,7 @@ static void test_init_zero_elem_size(void **state) {
     (void) state;
 
     ArrayList *arr = arraylist_init(64, 0);
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
     arraylist_destroy(&arr);
 }
 
@@ -37,18 +39,20 @@ static void test_init_large_capacity(void **state) {
     (void) state;
 
     ArrayList *arr = arraylist_init(SIZE_MAX, sizeof(int));
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
     arraylist_destroy(&arr);
 }
 
+// DESTROY
+ 
 static void test_destroy_valid_array(void **state) {
     (void) state;
 
     ArrayList *arr = arraylist_init(64, sizeof(int));
-    assert_ptr_not_equal(arr, NULL);
+    assert_non_null(arr);
 
     arraylist_destroy(&arr);
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
 }
 
 static void test_destroy_null_array(void **state) {
@@ -57,7 +61,7 @@ static void test_destroy_null_array(void **state) {
     ArrayList *arr = NULL;
     ArrayListErr err = arraylist_destroy(&arr);
 
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
     assert_int_equal(err, ARRLIST_NULL_ARG);
 }
 
@@ -65,15 +69,107 @@ static void test_destroy_double(void **state) {
     (void) state;
 
     ArrayList *arr = arraylist_init(64, sizeof(int));
-    assert_ptr_not_equal(arr, NULL);
+    assert_non_null(arr);
 
     ArrayListErr err = arraylist_destroy(&arr);
     assert_int_equal(err, ARRLIST_OK);
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
 
     err = arraylist_destroy(&arr);
     assert_int_equal(err, ARRLIST_NULL_ARG);
-    assert_ptr_equal(arr, NULL);
+    assert_null(arr);
+}
+
+// State
+static void test_capacity_after_init(void **state) {
+    (void) state;
+
+    ArrayList *arr = arraylist_init(64, sizeof(int));
+    assert_non_null(arr);
+
+    assert_int_equal(arraylist_capacity(arr), 64);
+
+    arraylist_destroy(&arr);
+}
+
+static void test_is_empty_after_init(void **state) {
+    (void) state;
+
+    ArrayList *arr = arraylist_init(64, sizeof(int));
+    assert_non_null(arr);
+
+    assert_true(arraylist_is_empty(arr));
+
+    arraylist_destroy(&arr);
+}
+
+static void test_is_empty_after_push(void **state) {
+    (void) state;
+
+    ArrayList *arr = arraylist_init(64, sizeof(int));
+    assert_non_null(arr);
+
+    int n = 8;
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    
+    assert_false(arraylist_is_empty(arr));
+
+    arraylist_destroy(&arr);
+}
+
+static void test_size_after_many_push(void **state) {
+    (void) state;
+
+    ArrayList *arr = arraylist_init(64, sizeof(int));
+    assert_non_null(arr);
+
+    int n = 8;
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_size(arr), 1);
+
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_size(arr), 2);
+
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_size(arr), 3);
+
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_size(arr), 4);
+
+    arraylist_destroy(&arr);
+}
+
+static void test_capacity_growth_on_push(void **state) {
+    (void) state;
+
+    ArrayList *arr = arraylist_init(2, sizeof(int));
+    assert_non_null(arr);
+
+    int n = 8;
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_capacity(arr), 2);
+
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_capacity(arr), 2);
+
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_capacity(arr), 4);
+
+    arraylist_destroy(&arr);
+}
+
+static void test_capacity_shrink_on_pop(void **state) {
+    (void) state;
+
+    ArrayList *arr = arraylist_init(8, sizeof(int));
+    assert_non_null(arr);
+
+    int n = 8;
+    assert_int_equal(arraylist_push_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_pop_back(arr, &n), ARRLIST_OK);
+    assert_int_equal(arraylist_capacity(arr), 4);
+
+    arraylist_destroy(&arr);
 }
 
 int main(void) {
@@ -90,10 +186,20 @@ int main(void) {
         cmocka_unit_test(test_destroy_double),
     };
 
+    const struct CMUnitTest state[] = {
+        cmocka_unit_test(test_capacity_after_init),
+        cmocka_unit_test(test_is_empty_after_init),
+        cmocka_unit_test(test_is_empty_after_push),
+        cmocka_unit_test(test_size_after_many_push),
+        cmocka_unit_test(test_capacity_growth_on_push),
+        cmocka_unit_test(test_capacity_shrink_on_pop),
+    };
+
     int rc = 0;
 
     rc += cmocka_run_group_tests(init, NULL, NULL);
     rc += cmocka_run_group_tests(destroy, NULL, NULL);
+    rc += cmocka_run_group_tests(state, NULL, NULL);
 
     return rc;
 }