Fix an integer wrap around bug and add a couple more tests

1 files changed, 33 insertions, 0 deletions

diff --git a/tests/test_megolm.cpp b/tests/test_megolm.cpp
index bf53346..3048fa3 100644
--- a/tests/test_megolm.cpp
+++ b/tests/test_megolm.cpp
@@ -98,4 +98,37 @@ std::uint8_t random_bytes[] =
     assert_equals(megolm_get_data(&mr2), megolm_get_data(&mr1), MEGOLM_RATCHET_LENGTH);
 }
 
+{
+    TestCase test_case("Megolm::advance overflow by one");
+
+    Megolm mr1, mr2;
+
+    megolm_init(&mr1, random_bytes, 0xffffffffUL);
+    megolm_advance_to(&mr1, 0x0);
+    assert_equals(0x0U, mr1.counter);
+
+    megolm_init(&mr2, random_bytes, 0xffffffffUL);
+    megolm_advance(&mr2);
+    assert_equals(0x0U, mr2.counter);
+
+    assert_equals(megolm_get_data(&mr2), megolm_get_data(&mr1), MEGOLM_RATCHET_LENGTH);
+}
+
+{
+    TestCase test_case("Megolm::advance overflow");
+
+    Megolm mr1, mr2;
+
+    megolm_init(&mr1, random_bytes, 0x1UL);
+    megolm_advance_to(&mr1, 0x80000000UL);
+    megolm_advance_to(&mr1, 0x0);
+    assert_equals(0x0U, mr1.counter);
+
+    megolm_init(&mr2, random_bytes, 0x1UL);
+    megolm_advance_to(&mr2, 0x0UL);
+    assert_equals(0x0U, mr2.counter);
+
+    assert_equals(megolm_get_data(&mr2), megolm_get_data(&mr1), MEGOLM_RATCHET_LENGTH);
+}
+
 }