fixed seqid test, added timestamp extraction

2026-07-10 22:06:37 +04:00
parent 566c813e8d
commit 8e961352d2
4 changed files with 188 additions and 7 deletions
@@ -0,0 +1,141 @@
+namespace Just.Core.Tests.GuidV8Tests;
+
+public class ExtractTimestamp
+{
+    [Fact]
+    public void RoundTrip_ShouldReturnOriginalTimestamp()
+    {
+        var original = new DateTime(2026, 7, 10, 21, 30, 0, DateTimeKind.Utc);
+
+        var guid = GuidV8.NewGuid(original, RngEntropy.Weak);
+        var extracted = GuidV8.ExtractTimestamp(guid);
+
+        extracted.ShouldBe(original);
+        extracted.Kind.ShouldBe(DateTimeKind.Utc);
+    }
+
+    [Fact]
+    public void RoundTrip_ShouldPreserve100MicrosecondPrecision()
+    {
+        // 100-microsecond precision: 1234567 * 100µs = 123456.7ms
+        var original = new DateTime(2024, 3, 15, 8, 45, 30, 123, DateTimeKind.Utc)
+            .AddTicks(4567); // sub-millisecond ticks
+
+        var guid = GuidV8.NewGuid(original, RngEntropy.Weak);
+        var extracted = GuidV8.ExtractTimestamp(guid);
+
+        // 123ms + 4567 ticks = 123ms + 456.7µs
+        // timestamp = (ticks since epoch) / 1000 (100µs units)
+        // Ticks: 123ms = 1,230,000 ticks; + 4,567 ticks = 1,234,567 ticks
+        // timestamp = 1,234,567 / 1000 = 1234 (truncates last 3 digits)
+        // recovered = 1234 * 1000 = 1,234,000 ticks = 123.4ms
+        // So the sub-100µs part (67 ticks) is lost
+        extracted.ShouldBe(new DateTime(2024, 3, 15, 8, 45, 30, 123, DateTimeKind.Utc)
+            .AddTicks(4000)); // 123.4ms
+    }
+
+    [Fact]
+    public void RoundTrip_UnixEpoch_ShouldReturnExactEpoch()
+    {
+        var original = DateTime.UnixEpoch;
+
+        var guid = GuidV8.NewGuid(original, RngEntropy.Weak);
+        var extracted = GuidV8.ExtractTimestamp(guid);
+
+        extracted.ShouldBe(original);
+    }
+
+    [Fact]
+    public void RoundTrip_PreUnixEpoch_ShouldThrowArgumentException()
+    {
+        // Negative timestamps cannot be encoded correctly because the uint casts
+        // in NewGuid corrupt the sign. The encoding should reject them.
+        var preEpoch = new DateTime(1969, 7, 20, 20, 17, 40, DateTimeKind.Utc);
+
+        Action act = () => GuidV8.NewGuid(preEpoch);
+
+        act.ShouldThrow<ArgumentException>();
+    }
+
+    [Fact]
+    public void RoundTrip_FarFuture_ShouldPreserveTimestamp()
+    {
+        // Year 2200 — well within 48-bit range
+        var original = new DateTime(2200, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+
+        var guid = GuidV8.NewGuid(original, RngEntropy.Weak);
+        var extracted = GuidV8.ExtractTimestamp(guid);
+
+        extracted.ShouldBe(original);
+    }
+
+    [Fact]
+    public void ExtractTimestamp_WithStrongEntropy_ShouldStillRecoverTimestamp()
+    {
+        var original = new DateTime(2025, 12, 25, 10, 0, 0, DateTimeKind.Utc);
+
+        var guid = GuidV8.NewGuid(original, RngEntropy.Strong);
+        var extracted = GuidV8.ExtractTimestamp(guid);
+
+        extracted.ShouldBe(original);
+    }
+
+    [Fact]
+    public void NonV8Guid_ShouldThrowArgumentException()
+    {
+        var guid = Guid.NewGuid(); // UUID v4
+
+        Action act = () => GuidV8.ExtractTimestamp(guid);
+
+        act.ShouldThrow<ArgumentException>()
+            .WithMessage("The provided GUID is not a UUID v8 (version=4). (Parameter 'guid')");
+    }
+
+    [Fact]
+    public void GuidEmpty_ShouldThrowArgumentException()
+    {
+        Action act = () => GuidV8.ExtractTimestamp(Guid.Empty);
+
+        act.ShouldThrow<ArgumentException>()
+            .WithMessage("The provided GUID is not a UUID v8 (version=0). (Parameter 'guid')");
+    }
+
+    [Fact]
+    public void MultipleRoundTrips_ShouldAllMatch()
+    {
+        var baseTime = new DateTime(2020, 1, 1, 0, 0, 0, DateTimeKind.Utc);
+
+        for (int i = 0; i < 100; i++)
+        {
+            var original = baseTime.AddMinutes(i * 37 + 13); // varied intervals
+            var guid = GuidV8.NewGuid(original, RngEntropy.Weak);
+            var extracted = GuidV8.ExtractTimestamp(guid);
+
+            extracted.ShouldBe(original);
+        }
+    }
+
+    [Fact]
+    public void ExtractTimestamp_ThenNewGuid_ShouldProduceSortableSequence()
+    {
+        var t1 = new DateTime(2026, 5, 1, 0, 0, 0, DateTimeKind.Utc);
+        var t2 = t1.AddSeconds(1);
+        var t3 = t2.AddSeconds(1);
+
+        var g1 = GuidV8.NewGuid(t1, RngEntropy.Weak);
+        var g2 = GuidV8.NewGuid(t2, RngEntropy.Weak);
+        var g3 = GuidV8.NewGuid(t3, RngEntropy.Weak);
+
+        var extracted1 = GuidV8.ExtractTimestamp(g1);
+        var extracted2 = GuidV8.ExtractTimestamp(g2);
+        var extracted3 = GuidV8.ExtractTimestamp(g3);
+
+        extracted1.ShouldBe(t1);
+        extracted2.ShouldBe(t2);
+        extracted3.ShouldBe(t3);
+
+        // Verify they sort in order
+        new[] { g3, g1, g2 }.Order().ShouldBe([g1, g2, g3]);
+        new[] { extracted3, extracted1, extracted2 }.Order().ShouldBe([t1, t2, t3]);
+    }
+}