[repo-assist] feat: add IsPositive, IsNegative, and IsZero predicates

src/FixedPointNano/FixedPointNano.cs

@@ -135,6 +135,30 @@ public static bool IsInteger(FixedPointNano value)
         return value.RawValue % Scale == 0;
     }
 
+    /// <summary>Returns <see langword="true"/> if <paramref name="value"/> is strictly greater than zero.</summary>
+    /// <param name="value">The value to test.</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsPositive(FixedPointNano value)
+    {
+        return value.RawValue > 0;
+    }
+
+    /// <summary>Returns <see langword="true"/> if <paramref name="value"/> is strictly less than zero.</summary>
+    /// <param name="value">The value to test.</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsNegative(FixedPointNano value)
+    {
+        return value.RawValue < 0;
+    }
+
+    /// <summary>Returns <see langword="true"/> if <paramref name="value"/> is exactly zero.</summary>
+    /// <param name="value">The value to test.</param>
+    [MethodImpl(MethodImplOptions.AggressiveInlining)]
+    public static bool IsZero(FixedPointNano value)
+    {
+        return value.RawValue == 0;
+    }
+
     public static FixedPointNano FromDecimal(decimal value)
     {
         var scaledValue = decimal.Round(value * Scale, 0, MidpointRounding.ToEven);

tests/FixedPointNano.Tests/FixedPointNanoTests.cs

@@ -36,6 +36,38 @@ public void IsIntegerShouldDetectWholeness()
         Assert.That(FixedPointNano.IsInteger(FixedPointNano.FromDecimal(-2m)), Is.True);
     }
 
+    [Test]
+    public void IsPositiveShouldReturnTrueOnlyForPositiveValues()
+    {
+        Assert.That(FixedPointNano.IsPositive(FixedPointNano.Zero), Is.False);
+        Assert.That(FixedPointNano.IsPositive(FixedPointNano.Epsilon), Is.True);
+        Assert.That(FixedPointNano.IsPositive(FixedPointNano.One), Is.True);
+        Assert.That(FixedPointNano.IsPositive(FixedPointNano.MaxValue), Is.True);
+        Assert.That(FixedPointNano.IsPositive(FixedPointNano.NegativeOne), Is.False);
+        Assert.That(FixedPointNano.IsPositive(FixedPointNano.MinValue), Is.False);
+    }
+
+    [Test]
+    public void IsNegativeShouldReturnTrueOnlyForNegativeValues()
+    {
+        Assert.That(FixedPointNano.IsNegative(FixedPointNano.Zero), Is.False);
+        Assert.That(FixedPointNano.IsNegative(FixedPointNano.Epsilon), Is.False);
+        Assert.That(FixedPointNano.IsNegative(FixedPointNano.One), Is.False);
+        Assert.That(FixedPointNano.IsNegative(FixedPointNano.MaxValue), Is.False);
+        Assert.That(FixedPointNano.IsNegative(FixedPointNano.NegativeOne), Is.True);
+        Assert.That(FixedPointNano.IsNegative(FixedPointNano.MinValue), Is.True);
+    }
+
+    [Test]
+    public void IsZeroShouldReturnTrueOnlyForZero()
+    {
+        Assert.That(FixedPointNano.IsZero(FixedPointNano.Zero), Is.True);
+        Assert.That(FixedPointNano.IsZero(FixedPointNano.Epsilon), Is.False);
+        Assert.That(FixedPointNano.IsZero(-FixedPointNano.Epsilon), Is.False);
+        Assert.That(FixedPointNano.IsZero(FixedPointNano.One), Is.False);
+        Assert.That(FixedPointNano.IsZero(FixedPointNano.NegativeOne), Is.False);
+    }
+
     [Test]
     public void FractionalPartShouldReturnDecimalComponent()
     {