implemented ISignedNumber

2026-09-13 23:08:27 +04:00
parent 082fd84c87
commit e51874b0c3
13 changed files with 1286 additions and 43 deletions
@@ -0,0 +1,70 @@
+using System.Globalization;
+using Shouldly;
+using Xunit;
+
+namespace Just.PreciseMath.Tests;
+
+public class DoubleDoubleSpanFormattingTests
+{
+    [Theory]
+    [InlineData("")]
+    [InlineData("G32")]
+    [InlineData("g999")]
+    [InlineData("E20")]
+    [InlineData("F54")]
+    public void SpanFormattingMatchesExactComponentFormatting(string format)
+    {
+        DoubleDouble value = DoubleDouble.FromComponents(1.0, Math.ScaleB(1.0, -54));
+        NumberFormatInfo provider = new() { NumberDecimalSeparator = "::", NegativeSign = "minus" };
+        string expected = value.ToString(format, provider);
+        char[] buffer = new char[expected.Length + 1];
+        buffer[^1] = '!';
+        ((ISpanFormattable)value).TryFormat(buffer.AsSpan(0, expected.Length), out int written, format, provider).ShouldBeTrue();
+        written.ShouldBe(expected.Length);
+        new string(buffer, 0, written).ShouldBe(expected);
+        buffer[^1].ShouldBe('!');
+    }
+
+    [Fact]
+    public void DefaultSpanFormattingRetainsLowComponentDigits()
+    {
+        Span<char> buffer = stackalloc char[64];
+        DoubleDouble.FromComponents(1.0, Math.ScaleB(1.0, -54))
+            .TryFormat(buffer, out int written, provider: CultureInfo.InvariantCulture).ShouldBeTrue();
+        buffer[..written].ToString().ShouldBe("1.0000000000000000555111512312578");
+    }
+
+    [Fact]
+    public void ShortDestinationIsUnchangedAndReportsZero()
+    {
+        char[] buffer = ['!', '!'];
+        DoubleDouble.PI.TryFormat(buffer, out int written, "G32", CultureInfo.InvariantCulture).ShouldBeFalse();
+        written.ShouldBe(0);
+        new string(buffer).ShouldBe("!!");
+        DoubleDouble.One.TryFormat(Span<char>.Empty, out written, provider: CultureInfo.InvariantCulture).ShouldBeFalse();
+        written.ShouldBe(0);
+    }
+
+    [Theory]
+    [InlineData(-0.0)]
+    [InlineData(double.NaN)]
+    [InlineData(double.PositiveInfinity)]
+    [InlineData(double.NegativeInfinity)]
+    public void SpanFormattingPreservesSpecialValues(double high)
+    {
+        NumberFormatInfo provider = new() { NegativeSign = "minus", NaNSymbol = "unknown" };
+        DoubleDouble value = new(high);
+        Span<char> buffer = stackalloc char[64];
+        value.TryFormat(buffer, out int written, "F2", provider).ShouldBeTrue();
+        buffer[..written].ToString().ShouldBe(value.ToString("F2", provider));
+    }
+
+    [Theory]
+    [InlineData("R")]
+    [InlineData("F1000")]
+    [InlineData("G-1")]
+    public void InvalidFormatThrowsEvenForEmptyDestination(string format)
+    {
+        Should.Throw<FormatException>(() => DoubleDouble.One.TryFormat(Span<char>.Empty, out _, format, CultureInfo.InvariantCulture));
+    }
+}