Refine by-divisor prime test time limits

PerfectNumbers.Core.Tests/MersenneNumberDivisorGpuTesterTests.cs

@@ -86,6 +86,17 @@ public class MersenneNumberDivisorGpuTesterTests
         exhausted.Should().BeTrue();
     }
 
+    [Fact]
+    [Trait("Category", "Fast")]
+    public void ByDivisor_gpu_prime_test_limit_stops_scan_immediately()
+    {
+        var tester = new MersenneNumberDivisorByDivisorGpuTester();
+        tester.ConfigureFromMaxPrime(43UL);
+
+        tester.IsPrime(31UL, out bool divisorsExhausted, TimeSpan.Zero).Should().BeTrue();
+        divisorsExhausted.Should().BeFalse();
+    }
+
     [Fact]
     [Trait("Category", "Fast")]
     public void ByDivisor_tester_requires_configuration()