final

BlueLaminate/BlueLaminate.Tests/Tradeups/TradeupMathTests.cs

@@ -0,0 +1,52 @@
+using BlueLaminate.Core.Tradeups;
+using Xunit;
+
+namespace BlueLaminate.Tests.Tradeups;
+
+public class TradeupMathTests
+{
+    [Fact]
+    public void NormalizedFraction_maps_value_into_its_own_range()
+    {
+        // Mid-point of a 0.06–0.80 range.
+        var frac = TradeupMath.NormalizedFraction(0.43m, 0.06m, 0.80m);
+        Assert.Equal(0.5m, frac, precision: 6);
+    }
+
+    [Theory]
+    [InlineData(-0.5)] // below min
+    [InlineData(2.0)]  // above max
+    public void NormalizedFraction_clamps_out_of_range_values(double value)
+    {
+        var frac = TradeupMath.NormalizedFraction((decimal)value, 0.0m, 1.0m);
+        Assert.InRange(frac, 0m, 1m);
+    }
+
+    [Fact]
+    public void NormalizedFraction_returns_zero_for_zero_width_range()
+    {
+        Assert.Equal(0m, TradeupMath.NormalizedFraction(0.3m, 0.3m, 0.3m));
+    }
+
+    [Fact]
+    public void OutputFloat_maps_average_fraction_onto_output_range()
+    {
+        // avg 0.10 onto a 0.00–0.70 output range → 0.07 (the FN/MW boundary).
+        var outFloat = TradeupMath.OutputFloat(0.10m, 0.00m, 0.70m);
+        Assert.Equal(0.07m, outFloat, precision: 6);
+    }
+
+    [Fact]
+    public void Full_contract_float_math_matches_hand_calculation()
+    {
+        // Ten inputs, each normalised to its own range, then averaged and mapped onto the
+        // output's 0.00–0.80 range. Five inputs at fraction 0.2 and five at 0.4 → avg 0.3.
+        var fractions = new[] { 0.2m, 0.2m, 0.2m, 0.2m, 0.2m, 0.4m, 0.4m, 0.4m, 0.4m, 0.4m };
+        var avg = fractions.Sum() / fractions.Length;
+        Assert.Equal(0.3m, avg, precision: 6);
+
+        var outFloat = TradeupMath.OutputFloat(avg, 0.00m, 0.80m);
+        Assert.Equal(0.24m, outFloat, precision: 6);
+        Assert.Equal(WearBand.FieldTested, WearBands.FromFloat(outFloat));
+    }
+}