#2973: False warning from xUnit1012 when using params string[]?

xunit · Jul 10, 2024 · 7f99c6a · 7f99c6a
1 parent 798f46c
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diff --git a/src/xunit.analyzers.tests/Analyzers/X1000/InlineDataMustMatchTheoryParametersTests.cs b/src/xunit.analyzers.tests/Analyzers/X1000/InlineDataMustMatchTheoryParametersTests.cs
@@ -27,6 +27,34 @@ public void TestMethod(params string[] args) { }
 			await Verify.VerifyAnalyzer(source);
 		}
 
+		[Fact]
+		public async Task MethodUsingNullParamsArgument_NonNullable()
+		{
+			var source = @"
+public class TestClass {
+    [Xunit.Theory]
+    [Xunit.InlineData(null)]
+    public void TestMethod(params string[] args) { }
+}";
+
+			await Verify.VerifyAnalyzer(source);
+		}
+
+		[Fact]
+		public async Task MethodUsingNullParamsArgument_Nullable()
+		{
+			var source = @"
+#nullable enable
+
+public class TestClass {
+    [Xunit.Theory]
+    [Xunit.InlineData(null)]
+    public void TestMethod(params string[]? args) { }
+}";
+
+			await Verify.VerifyAnalyzer(LanguageVersion.CSharp9, source);
+		}
+
 		[Fact]
 		public async Task MethodUsingNormalAndParamsArgument()
 		{
@@ -40,6 +68,34 @@ public void TestMethod(string first, params string[] args) { }
 			await Verify.VerifyAnalyzer(source);
 		}
 
+		[Fact]
+		public async Task MethodUsingNormalAndNullParamsArgument_NonNullable()
+		{
+			var source = @"
+public class TestClass {
+    [Xunit.Theory]
+    [Xunit.InlineData(""abc"", null)]
+    public void TestMethod(string first, params string[] args) { }
+}";
+
+			await Verify.VerifyAnalyzer(source);
+		}
+
+		[Fact]
+		public async Task MethodUsingNormalAndNullParamsArgument_Nullable()
+		{
+			var source = @"
+#nullable enable
+
+public class TestClass {
+    [Xunit.Theory]
+    [Xunit.InlineData(""abc"", null)]
+    public void TestMethod(string first, params string[]? args) { }
+}";
+
+			await Verify.VerifyAnalyzer(LanguageVersion.CSharp9, source);
+		}
+
 		[Fact]
 		public async Task MethodUsingNormalAndUnusedParamsArgument()
 		{

diff --git a/src/xunit.analyzers/X1000/InlineDataMustMatchTheoryParameters.cs b/src/xunit.analyzers/X1000/InlineDataMustMatchTheoryParameters.cs
@@ -123,6 +123,17 @@ public override void AnalyzeCompilation(
 
 					if (value.IsNull)
 					{
+						// Special case: if this is the only value of the params array, and it's null,
+						// and the params array itself is nullable, then this is allowable, since we'll
+						// end up passing null for the array itself.
+						if (paramsElementType is not null &&
+							valueIdx == values.Length - 1 &&
+							parameter.Type.NullableAnnotation == NullableAnnotation.Annotated)
+						{
+							valueIdx = values.Length;
+							break;
+						}
+
 						var isValueTypeParam =
 							paramsElementType is not null
 								? paramsElementType.IsValueType && paramsElementType.OriginalDefinition.SpecialType != SpecialType.System_Nullable_T