Initial commit.

EvenPerfectBitScanner.Tests/ProgramTests.cs

@@ -0,0 +1,92 @@
+using FluentAssertions;
+using Xunit;
+using PerfectNumbers.Core;
+using System.Reflection;
+
+namespace EvenPerfectBitScanner.Tests;
+
+[Trait("Category", "Fast")]
+public class ProgramTests
+{
+    [Fact]
+    public void CountOnes_returns_correct_count()
+    {
+        Program.CountOnes(0b101010UL).Should().Be(3UL);
+    }
+
+    [Theory]
+    [InlineData(2UL, true)]
+    [InlineData(4UL, false)]
+    [InlineData(9UL, false)]
+    [InlineData(11UL, true)]
+    [InlineData(81UL, false)]
+    public void IsPrime_identifies_primes_correctly(ulong n, bool expected)
+    {
+        new PrimeTester().IsPrime(n, CancellationToken.None).Should().Be(expected);
+    }
+
+    [Fact]
+    public void TransformPAdd_moves_to_next_candidate()
+    {
+        ulong remainder = 3UL;
+        Program.TransformPAdd(3UL, ref remainder).Should().Be(5UL);
+        Program.TransformPAdd(5UL, ref remainder).Should().Be(7UL);
+        Program.TransformPAdd(7UL, ref remainder).Should().Be(11UL);
+    }
+
+    [Fact]
+    public void TransformPBit_appends_one_bit_and_skips_to_candidate()
+    {
+        ulong remainder = 5UL;
+        Program.TransformPBit(5UL, ref remainder).Should().Be(13UL);
+    }
+
+    [Fact]
+    public void TransformPBit_detects_overflow_and_stops()
+    {
+        typeof(Program).GetField("_limitReached", BindingFlags.NonPublic | BindingFlags.Static)!
+            .SetValue(null, false);
+
+        ulong start = (ulong.MaxValue >> 1) + 1UL;
+        ulong remainder = start % 6UL;
+        Program.TransformPBit(start, ref remainder);
+
+        bool limit = (bool)typeof(Program).GetField("_limitReached", BindingFlags.NonPublic | BindingFlags.Static)!
+            .GetValue(null)!;
+        limit.Should().BeTrue();
+
+        typeof(Program).GetField("_limitReached", BindingFlags.NonPublic | BindingFlags.Static)!
+            .SetValue(null, false);
+    }
+
+    [Fact]
+    public void Gcd_filter_detects_some_composites()
+    {
+        Program.IsCompositeByGcd(15UL).Should().BeTrue();
+        Program.IsCompositeByGcd(5UL).Should().BeFalse();
+    }
+
+    [Fact]
+    [Trait("Category", "Fast")]
+    public void Main_displays_help_when_requested()
+    {
+        var main = typeof(Program).GetMethod("Main", BindingFlags.NonPublic | BindingFlags.Static)!;
+        using var writer = new StringWriter();
+        TextWriter original = Console.Out;
+        Console.SetOut(writer);
+
+        try
+        {
+            main.Invoke(null, [new[] { "--help" }]);
+        }
+        finally
+        {
+            Console.SetOut(original);
+        }
+
+        string output = writer.ToString();
+        output.Should().Contain("Usage:");
+        output.Should().Contain("--mersenne-device=cpu|gpu");
+        output.Should().Contain("--primes-device=cpu|gpu");
+    }
+}