补考、缓考成绩自动替换

tests/Jiaowu.Api.Tests/GradeCalculatorTests.cs

@@ -55,10 +55,18 @@ public sealed class GradeCalculatorTests
 
     [Theory]
     [InlineData(GradeExamStatus.Absent)]
-    [InlineData(GradeExamStatus.Deferred)]
     [InlineData(GradeExamStatus.Exempt)]
     public void Exceptional_exam_status_has_no_numeric_total(GradeExamStatus status)
     {
         Assert.Null(GradeCalculator.CalculateTotal(90, 90, [], 30, 70, [], status));
     }
+
+    [Fact]
+    public void Deferred_exam_uses_regular_and_final_scores_like_normal_exam()
+    {
+        var total = GradeCalculator.CalculateTotal(
+            83, 91, [], 30, 70, [], GradeExamStatus.Deferred);
+
+        Assert.Equal(88.6m, total);
+    }
 }