Detect & fix inverted NUnit asserts

meziantou · Dec 8, 2023 · 4bdd826 · 4bdd826
1 parent f83f98d
commit 4bdd826
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Showing 2 changed files with 94 additions and 9 deletions.
diff --git a/Meziantou.FluentAssertionsAnalyzers.Tests/NUnit4ToFluentAssertionsAnalyzerUnitTests.cs b/Meziantou.FluentAssertionsAnalyzers.Tests/NUnit4ToFluentAssertionsAnalyzerUnitTests.cs
@@ -564,4 +564,68 @@ public void MyTest()
               }
               """);
     }
+
+    [Theory]
+    [InlineData(@"ClassicAssert.AreEqual(test, 6)", @"test.Should().Be(6)")]
+    [InlineData(@"ClassicAssert.AreNotEqual(test, 6)", @"test.Should().NotBe(6)")]
+    [InlineData(@"ClassicAssert.AreEqual(test, ""test"")", @"test.Should().Be(""test"")")]
+    [InlineData(@"ClassicAssert.AreNotEqual(test, ""test"")", @"test.Should().NotBe(""test"")")]
+    public Task Assert_Inverted_Asserts(string code, string fix)
+    {
+        return Assert(
+            $$"""
+              using NUnit.Framework.Legacy;
+
+              class Test
+              {
+                  public void MyTest(object test)
+                  {
+                      [|{{code}}|];
+                  }
+              }
+              """,
+            $$"""
+              using FluentAssertions;
+              using NUnit.Framework.Legacy;
+
+              class Test
+              {
+                  public void MyTest(object test)
+                  {
+                      {{fix}};
+                  }
+              }
+              """);
+    }
+
+    [Theory]
+    [InlineData(@"ClassicAssert.AreEqual(test, 6.0, delta: 2.0)", @"test.Should().BeApproximately(6.0, 2.0)")]
+    [InlineData(@"ClassicAssert.AreEqual(test, 6.0)", @"test.Should().Be(6.0)")]
+    public Task Assert_Inverted_Asserts_double(string code, string fix)
+    {
+        return Assert(
+            $$"""
+              using NUnit.Framework.Legacy;
+
+              class Test
+              {
+                  public void MyTest(double test)
+                  {
+                      [|{{code}}|];
+                  }
+              }
+              """,
+            $$"""
+              using FluentAssertions;
+              using NUnit.Framework.Legacy;
+
+              class Test
+              {
+                  public void MyTest(double test)
+                  {
+                      {{fix}};
+                  }
+              }
+              """);
+    }
 }
diff --git a/Meziantou.FluentAssertionsAnalyzers/NunitAssertAnalyzerCodeFixProvider.cs b/Meziantou.FluentAssertionsAnalyzers/NunitAssertAnalyzerCodeFixProvider.cs
@@ -178,18 +178,17 @@ private static async Task<Document> Rewrite(Document document, SyntaxNode nodeTo
         {
             if (methodName is "AreEqual")
             {
-                if (method.Parameters[0].Type.SpecialType == SpecialType.System_Double)
-                {
-                    result = rewrite.UsingShould(arguments[1], "BeApproximately", ArgumentList(arguments[0], arguments.Skip(2)));
-                }
-                else
-                {
-                    result = rewrite.UsingShould(arguments[1], "Be", ArgumentList(arguments[0], arguments.Skip(2)));
-                }
+                var (left, right) = GetLeftRight(arguments, semanticModel, cancellationToken);
+
+                var useBeApproximately = semanticModel.GetTypeInfo(left.Expression, cancellationToken).Type?.SpecialType == SpecialType.System_Double 
+                    && arguments.FirstOrDefault(x => x.NameColon?.Name.Identifier.ValueText is "delta") is not null;
+
+                result = rewrite.UsingShould(right, useBeApproximately ? "BeApproximately" : "Be", ArgumentList(left, arguments.Skip(2)));
             }
             else if (methodName is "AreNotEqual")
             {
-                result = rewrite.UsingShould(arguments[1], "NotBe", ArgumentList(arguments[0], arguments.Skip(2)));
+                var (left, right) = GetLeftRight(arguments, semanticModel, cancellationToken);
+                result = rewrite.UsingShould(right, "NotBe", ArgumentList(left, arguments.Skip(2)));
             }
             else if (methodName is "AreSame")
             {
@@ -855,6 +854,28 @@ bool IsGenericMethod(out ITypeSymbol typeArgument, ITypeSymbol root, params stri
         return document;
     }
 
+    private static (ArgumentSyntax left, ArgumentSyntax right) GetLeftRight(SeparatedSyntaxList<ArgumentSyntax> arguments, SemanticModel semanticModel, CancellationToken cancellationToken)
+    {
+        var left = arguments[0];
+        var right = arguments[1];
+        var leftValue = semanticModel.GetConstantValue(left.Expression, cancellationToken);
+        var rightValue = semanticModel.GetConstantValue(right.Expression, cancellationToken);
+
+        // Don't invert if both are constant
+        if (leftValue.HasValue && rightValue.HasValue)
+        {
+            return (left, right);
+        }
+
+        // Invert if right is constant
+        if (rightValue.HasValue)
+        {
+            return (right, left);
+        }
+
+        return (left, right);
+    }
+
     private static ITypeSymbol GetConstantTypeValue(SemanticModel semanticModel, ExpressionSyntax expression, CancellationToken cancellationToken)
     {
         var operation = semanticModel.GetOperation(expression, cancellationToken);