chore(uuid): add more tests

tests/test_uuid.cpp

@@ -2,8 +2,15 @@
 
 #include <cpputils/uuid.h>
 #include <array>
+#include <chrono>
+#include <cstddef>
+#include <string>
+#include <thread>
+#include <unordered_set>
 
-TEST_CASE("uuidToString formats UUIDs correctly") {
+using namespace cpputils::uuid;
+
+TEST_CASE("uuidToString formats UUIDs correctly", "[uuid]") {
 
   struct TestVector {
     std::array<uint8_t, 16> uuid;
@@ -38,6 +45,101 @@ TEST_CASE("uuidToString formats UUIDs correctly") {
   };
 
   for (auto const& t : tests) {
-    REQUIRE(cpputils::uuid::uuidToString(t.uuid) == t.expected);
+    REQUIRE(uuidToString(t.uuid) == t.expected);
   }
 }
+
+TEST_CASE("V4 generates unique UUIDs", "[uuid][v4]") {
+  V4 generator;
+
+  constexpr int N = 1000;
+  std::unordered_set<std::string> uuids;
+
+  for (int i = 0; i < N; ++i) {
+    auto uuid = generator.generate();
+    auto str = uuidToString(uuid);
+    REQUIRE(uuids.find(str) == uuids.end());
+    uuids.insert(str);
+  }
+}
+
+TEST_CASE("V7 generates increasing timestamps", "[uuid][v7]") {
+  V7 generator;
+
+  constexpr int N = 1000;
+  int64_t prev_ts = 0;
+
+  for (int i = 0; i < N; ++i) {
+    auto uuid = generator.generate();
+    auto ts = V7::get_timestamp_from_uuid(uuid);
+    REQUIRE(ts >= prev_ts);
+    prev_ts = ts;
+  }
+}
+
+TEST_CASE("V7 sequence increments on same timestamp", "[uuid][v7][!mayfail]") {
+  INFO("info message");
+  V7 generator;
+
+  size_t count = 0;
+  size_t i = 1000;
+  for (; i > 0;) {
+    auto uuid1 = generator.generate();
+    auto uuid2 = generator.generate();
+
+    auto ts1 = V7::get_timestamp_from_uuid(uuid1);
+    auto ts2 = V7::get_timestamp_from_uuid(uuid2);
+
+    if (ts1 == ts2) {
+      REQUIRE(uuid1 != uuid2);
+      count++;
+      if (count >= 10) {
+        break;
+      }
+    } else {
+      i--;
+    }
+  }
+  INFO(
+      "Testing that V7 UUIDs with the same timestamp produce unique UUIDs. "
+      "Tries up to 1000 pairs to avoid long runtime if UUID generation is "
+      "slow. "
+      "(Test fails with 0 > 0 if no same-timestamp UUIDs could be generated)");
+  REQUIRE(i > 0);
+}
+
+TEST_CASE("UUID string formatting consistency", "[uuid]") {
+  V4 v4;
+  V7 v7;
+
+  auto uuid4 = v4.generate();
+  auto uuid7 = v7.generate();
+
+  auto str4 = uuidToString(uuid4);
+  auto str7 = uuidToString(uuid7);
+
+  REQUIRE(str4.size() == 36);
+  REQUIRE(str7.size() == 36);
+
+  auto is_hex_or_dash = [](char c) {
+    return (c >= '0' && c <= '9') || (c >= 'a' && c <= 'f') || (c == '-');
+  };
+  REQUIRE(std::all_of(str4.begin(), str4.end(), is_hex_or_dash));
+  REQUIRE(std::all_of(str7.begin(), str7.end(), is_hex_or_dash));
+}
+
+TEST_CASE("V4 and V7 generate large number of UUIDs without collision",
+          "[uuid][stress]") {
+  V4 v4;
+  V7 v7;
+
+  constexpr int N = 5000;
+  std::unordered_set<std::string> uuids;
+
+  for (int i = 0; i < N; ++i) {
+    uuids.insert(uuidToString(v4.generate()));
+    uuids.insert(uuidToString(v7.generate()));
+  }
+
+  REQUIRE(uuids.size() == 2 * N);
+}