test-gap backlog fixes

2026-09-13 23:34:43 +04:00
parent e51874b0c3
commit e05e1e902a
5 changed files with 681 additions and 0 deletions
@@ -6,6 +6,30 @@ namespace Just.PreciseMath.Tests;

 public class DoubleDoubleFormattingTests
 {
+    [Theory]
+    [InlineData("G0")]
+    [InlineData("g0")]
+    public void ZeroGeneralPrecisionUses32SignificantDigits(string format)
+    {
+        // Exact dyadic 1 + 2^-54, rounded in decimal to 32 significant digits.
+        DoubleDouble value = DoubleDouble.FromComponents(1.0, Math.ScaleB(1.0, -54));
+        const string expected = "1.0000000000000000555111512312578";
+        value.ToString(format, CultureInfo.InvariantCulture).ShouldBe(expected);
+        ((IFormattable)value).ToString(format, CultureInfo.InvariantCulture).ShouldBe(expected);
+        Span<char> destination = stackalloc char[64];
+        value.TryFormat(destination, out int written, format, CultureInfo.InvariantCulture).ShouldBeTrue();
+        destination[..written].ToString().ShouldBe(expected);
+
+        // A zero residual lets the independent BCL G32 formatter supply the oracle,
+        // including the scientific-notation threshold and exponent letter case.
+        string referenceFormat = format[0] == 'G' ? "G32" : "g32";
+        foreach (double scalar in new double[] { 1e31, 1e32, 1e-5, -0.0, double.Epsilon, double.MaxValue })
+        {
+            new DoubleDouble(scalar).ToString(format, CultureInfo.InvariantCulture)
+                .ShouldBe(scalar.ToString(referenceFormat, CultureInfo.InvariantCulture));
+        }
+    }
+
    [Fact]
    public void GeneralFormattingTrimsOnlyFractionalZerosAtMaximumPrecision()
    {