Update xUnit1004 to not trigger with SkipWhen or SkipUnless (#193)

Author: joaonunomota

src/xunit.analyzers.tests/Analyzers/X1000/TestMethodShouldNotBeSkippedTests.cs

@@ -1,4 +1,5 @@
 using System.Threading.Tasks;
+using Microsoft.CodeAnalysis.CSharp;
 using Xunit;
 using Verify = CSharpVerifier<Xunit.Analyzers.TestMethodShouldNotBeSkipped>;
 
@@ -33,4 +34,36 @@ public void TestMethod() {{ }}
 
 		await Verify.VerifyAnalyzer(source);
 	}
+
+	[Theory]
+	[InlineData("Fact")]
+	[InlineData("Theory")]
+	public async Task SkippedTestWhenConditionIsTrue_V3_DoesNotTrigger(string attribute)
+	{
+		var source = string.Format(/* lang=c#-test */ """
+			public class TestClass {{
+				public static bool Condition {{ get; set; }}
+				[Xunit.{0}(Skip="Lazy", SkipWhen=nameof(Condition))]
+				public void TestMethod() {{ }}
+			}}
+			""", attribute);
+
+		await Verify.VerifyAnalyzerV3(LanguageVersion.CSharp7, source);
+	}
+
+	[Theory]
+	[InlineData("Fact")]
+	[InlineData("Theory")]
+	public async Task SkippedTestUnlessConditionIsTrue_V3_DoesNotTrigger(string attribute)
+	{
+		var source = string.Format(/* lang=c#-test */ """
+			public class TestClass {{
+				public static bool Condition {{ get; set; }}
+				[Xunit.{0}(Skip="Lazy", SkipUnless=nameof(Condition))]
+				public void TestMethod() {{ }}
+			}}
+			""", attribute);
+
+		await Verify.VerifyAnalyzerV3(LanguageVersion.CSharp7, source);
+	}
 }

src/xunit.analyzers/X1000/TestMethodShouldNotBeSkipped.cs

@@ -1,4 +1,3 @@
-using System.Linq;
 using Microsoft.CodeAnalysis;
 using Microsoft.CodeAnalysis.CSharp;
 using Microsoft.CodeAnalysis.CSharp.Syntax;
@@ -26,8 +25,21 @@ public override void AnalyzeCompilation(
 				return;
 			if (context.Node is not AttributeSyntax attribute)
 				return;
+			if (attribute.ArgumentList is null)
+				return;
+
+			var skipArgument = default(AttributeArgumentSyntax);
+			foreach (var argument in attribute.ArgumentList.Arguments)
+			{
+				var valueText = argument.NameEquals?.Name?.Identifier.ValueText;
+
+				if (valueText == "SkipWhen" || valueText == "SkipUnless")
+					return;
+
+				if (valueText == "Skip")
+					skipArgument = argument;
+			}
 
-			var skipArgument = attribute.ArgumentList?.Arguments.FirstOrDefault(arg => arg.NameEquals?.Name?.Identifier.ValueText == "Skip");
 			if (skipArgument is null)
 				return;