diff --git a/.drone.yml b/.drone.yml
index 64256df..1fa30e9 100644
--- a/.drone.yml
+++ b/.drone.yml
@@ -21,8 +21,8 @@ steps:
     image: gcc:12.2.0
     commands:
       - cd algo2/pairingheap
-      - gcc -Wall -Werror -o main pairingheap.c
-      - ./main
+      - gcc -Wall -Werror -o tests tests.c
+      - ./tests
   - name: radixheap
     image: gcc:12.2.0
     commands:
diff --git a/algo2/pairingheap/pairingheap.c b/algo2/pairingheap/pairingheap.c
index cff53ee..d511d25 100644
--- a/algo2/pairingheap/pairingheap.c
+++ b/algo2/pairingheap/pairingheap.c
@@ -160,23 +160,9 @@ struct PHeapNode *ph_deletemin(struct PHeap *ph) {
     return m;
 }
 
-int main() {
-    srand(2309);
-
-    struct PHeap ph;
-    ph_init(&ph);
-
-    for (int i = 0; i < 15; i++) {
-        ph_insert_malloc(&ph, rand() % 100);
-    }
-
-    ph_print(&ph);
-
-    while (ph.min != NULL) {
-        struct PHeapNode *h = ph_deletemin(&ph);
-        printf("deleteMin: %d\n", h->key);
+void ph_deinit_free(struct PHeap *ph) {
+    while (ph->min != NULL) {
+        struct PHeapNode *h = ph_deletemin(ph);
         free(h);
     }
-
-    ph_print(&ph);
 }
diff --git a/algo2/pairingheap/tests.c b/algo2/pairingheap/tests.c
new file mode 100644
index 0000000..59f9e32
--- /dev/null
+++ b/algo2/pairingheap/tests.c
@@ -0,0 +1,86 @@
+#include <stdio.h>
+#include <stdlib.h>
+#include <limits.h>
+
+#include "pairingheap.c"
+
+int tests_passed = 0;
+char *current_label;
+int current_num;
+
+#define TEST(LABEL, BLOCK) \
+current_label = LABEL; \
+current_num = __COUNTER__ + 1; \
+BLOCK; \
+fprintf(stderr, "[%3d] \x1b[32m%s ✓\x1b[0m\n", current_num, current_label); \
+tests_passed++;
+
+#define ASSERT(EXPR) \
+if (!(EXPR)) { \
+  fprintf(stderr, "[%3d] \x1b[31m%s ❌\x1b[0m\n", current_num, current_label); \
+  fprintf(stderr, "       Assertion failed in %s:%d:\n", __FILE__, __LINE__); \
+  fprintf(stderr, "       " #EXPR "\n"); \
+  goto after_tests; \
+}
+
+#define DONE \
+after_tests: { \
+  int tests_total = __COUNTER__; \
+  fprintf(stderr, "[\x1b[%dm***\x1b[0m] %d/%d tests passed.\n", tests_passed == tests_total ? 32 : 31, tests_passed, tests_total); \
+  if (tests_passed != tests_total) exit(1); \
+}
+
+int cmp_int(const void *a, const void *b) {
+    return *((int *) a) - *((int *) b);
+}
+
+int main() {
+    TEST("consecutive deleteMin calls yield increasing results", {
+        srand(2309);
+    
+        struct PHeap ph;
+        ph_init(&ph);
+
+        for (int i = 0; i < 1000; i++) {
+            ph_insert_malloc(&ph, rand());
+        }
+
+        int max = INT_MIN;
+        while (ph.min != NULL) {
+            struct PHeapNode *h = ph_deletemin(&ph);
+            ASSERT(h->key >= max);
+            max = h->key;
+            free(h);
+        }
+
+        ph_deinit_free(&ph);
+    })
+
+    TEST("deleteMin yields the same order as qsort", {
+        srand(2309);
+
+        struct PHeap ph;
+        ph_init(&ph);
+
+        int n = 1000;
+        int xs[n];
+
+        for (int i = 0; i < n; i++) {
+            xs[i] = rand();
+            ph_insert_malloc(&ph, xs[i]);
+        }
+
+        qsort(xs, n, sizeof(int), cmp_int);
+
+        for (int i = 0; i < n; i++) {
+            struct PHeapNode *h = ph_deletemin(&ph);
+            ASSERT(h->key == xs[i]);
+            free(h);
+        }
+        ASSERT(ph.min == NULL);
+
+        ph_deinit_free(&ph);
+    })
+
+    DONE
+}