File: src\Analyzers\CSharp\Tests\UseDefaultLiteral\UseDefaultLiteralTests.cs
Web Access
Project: src\src\Features\CSharpTest\Microsoft.CodeAnalysis.CSharp.Features.UnitTests.csproj (Microsoft.CodeAnalysis.CSharp.Features.UnitTests)
// Licensed to the .NET Foundation under one or more agreements.
// The .NET Foundation licenses this file to you under the MIT license.
// See the LICENSE file in the project root for more information.
 
using System.Threading.Tasks;
using Microsoft.CodeAnalysis.CSharp;
using Microsoft.CodeAnalysis.CSharp.UseDefaultLiteral;
using Microsoft.CodeAnalysis.Editor.UnitTests.CodeActions;
using Microsoft.CodeAnalysis.Test.Utilities;
using Roslyn.Test.Utilities;
using Xunit;
 
namespace Microsoft.CodeAnalysis.Editor.CSharp.UnitTests.UseDefaultLiteral;
 
using VerifyCS = CSharpCodeFixVerifier<
    CSharpUseDefaultLiteralDiagnosticAnalyzer,
    CSharpUseDefaultLiteralCodeFixProvider>;
 
[Trait(Traits.Feature, Traits.Features.CodeActionsUseDefaultLiteral)]
public class UseDefaultLiteralTests
{
    [Fact]
    public async Task TestNotInCSharp7()
    {
        var code = """
            class C
            {
                void Goo(string s = default(string))
                {
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInParameterList()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo(string s = [|default(string)|])
                    {
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo(string s = default)
                    {
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInIfCheck()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo(string s)
                    {
                        if (s == [|default(string)|]) { }
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo(string s)
                    {
                        if (s == default) { }
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInReturnStatement()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    string Goo()
                    {
                        return [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    string Goo()
                    {
                        return default;
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInReturnStatement2()
    {
        var code = """
            class C
            {
                string Goo()
                {
                    return {|CS0029:default(int)|};
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInLambda1()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                using System;
 
                class C
                {
                    void Goo()
                    {
                        Func<string> f = () => [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                using System;
 
                class C
                {
                    void Goo()
                    {
                        Func<string> f = () => default;
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInLambda2()
    {
        var code = """
            using System;
 
            class C
            {
                void Goo()
                {
                    Func<string> f = () => {|CS1662:{|CS0029:default(int)|}|};
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInLocalInitializer()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo()
                    {
                        string s = [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo()
                    {
                        string s = default;
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInLocalInitializer2()
    {
        var code = """
            class C
            {
                void Goo()
                {
                    string s = {|CS0029:default(int)|};
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotForVar()
    {
        var code = """
            class C
            {
                void Goo()
                {
                    var s = default(string);
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInInvocationExpression()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo()
                    {
                        Bar([|default(string)|]);
                    }
 
                    void Bar(string s) { }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo()
                    {
                        Bar(default);
                    }
 
                    void Bar(string s) { }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotWithMultipleOverloads()
    {
        var code = """
            class C
            {
                void Goo()
                {
                    Bar(default(string));
                }
 
                void Bar(string s) { }
                void Bar(int i) { }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestLeftSideOfTernary()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo(bool b)
                    {
                        var v = b ? [|default(string)|] : [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo(bool b)
                    {
                        var v = b ? default : default(string);
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1,
            DiagnosticSelector = d => d[0],
            CodeFixTestBehaviors = Testing.CodeFixTestBehaviors.FixOne | Testing.CodeFixTestBehaviors.SkipFixAllCheck
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestRightSideOfTernary()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo(bool b)
                    {
                        var v = b ? [|default(string)|] : [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo(bool b)
                    {
                        var v = b ? default(string) : default;
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1,
            DiagnosticSelector = d => d[1],
            CodeFixTestBehaviors = Testing.CodeFixTestBehaviors.FixOne | Testing.CodeFixTestBehaviors.SkipFixAllCheck
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestFixAll1()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo()
                    {
                        string s1 = [|default(string)|];
                        string s2 = [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo()
                    {
                        string s1 = default;
                        string s2 = default;
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestFixAll2()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo(bool b)
                    {
                        string s1 = b ? [|default(string)|] : [|default(string)|];
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo(bool b)
                    {
                        string s1 = b ? default : default(string);
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestFixAll3()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void Goo()
                    {
                        string s1 = [|default(string)|];
                        string s2 = {|CS0029:default(int)|};
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void Goo()
                    {
                        string s1 = default;
                        string s2 = {|CS0029:default(int)|};
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestDoNotOfferIfTypeWouldChange()
    {
        var code = """
            struct S
            {
                void M()
                {
                    var s = new S();
                    s.Equals(default(S));
                }
 
                public override bool Equals(object obj)
                {
                    return base.Equals(obj);
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestDoNotOfferIfTypeWouldChange2()
    {
        var code = """
            struct S<T>
            {
                void M()
                {
                    var s = new S<int>();
                    s.Equals(default(S<int>));
                }
 
                public override bool Equals(object obj)
                {
                    return base.Equals(obj);
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestOnShadowedMethod()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                struct S
                {
                    void M()
                    {
                        var s = new S();
                        s.Equals([|default(S)|]);
                    }
 
                    public new bool Equals(S s) => true;
                }
                """,
            FixedCode = """
                struct S
                {
                    void M()
                    {
                        var s = new S();
                        s.Equals(default);
                    }
 
                    public new bool Equals(S s) => true;
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact, WorkItem("https://github.com/dotnet/roslyn/issues/25456")]
    public async Task TestNotInSwitchCase()
    {
        var code = """
            class C
            {
                void M()
                {
                    switch (true)
                    {
                        case default(bool):
                    }
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotInSwitchCase_InsideParentheses()
    {
        var code = """
            class C
            {
                void M()
                {
                    switch (true)
                    {
                        case (default(bool)):
                    }
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInSwitchCase_InsideCast()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void M()
                    {
                        switch (true)
                        {
                            case (bool)[|default(bool)|]:
                        }
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void M()
                    {
                        switch (true)
                        {
                            case (bool)default:
                        }
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotInPatternSwitchCase()
    {
        var code = """
            class C
            {
                void M()
                {
                    switch (true)
                    {
                        case default(bool) when true:
                    }
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotInPatternSwitchCase_InsideParentheses()
    {
        var code = """
            class C
            {
                void M()
                {
                    switch (true)
                    {
                        case (default(bool)) when true:
                    }
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInPatternSwitchCase_InsideCast()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void M()
                    {
                        switch (true)
                        {
                            case (bool)[|default(bool)|] when true:
                        }
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void M()
                    {
                        switch (true)
                        {
                            case (bool)default when true:
                        }
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInPatternSwitchCase_InsideWhenClause()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void M()
                    {
                        switch (true)
                        {
                            case default(bool) when [|default(bool)|]:
                        }
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void M()
                    {
                        switch (true)
                        {
                            case default(bool) when default:
                        }
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotInPatternIs()
    {
        var code = """
            class C
            {
                void M()
                {
                    if (true is default(bool));
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestNotInPatternIs_InsideParentheses()
    {
        var code = """
            class C
            {
                void M()
                {
                    if (true is (default(bool)));
                }
            }
            """;
 
        await new VerifyCS.Test()
        {
            TestCode = code,
            FixedCode = code,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
 
    [Fact]
    public async Task TestInPatternIs_InsideCast()
    {
        await new VerifyCS.Test
        {
            TestCode = """
                class C
                {
                    void M()
                    {
                        if (true is (bool)[|default(bool)|]);
                    }
                }
                """,
            FixedCode = """
                class C
                {
                    void M()
                    {
                        if (true is (bool)default);
                    }
                }
                """,
            LanguageVersion = LanguageVersion.CSharp7_1
        }.RunAsync();
    }
}