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Merge pull request #1187 from progressonderwijs/robin/add-analyzer
add IfNotFalseAnalyzer
2 parents 12d8af5 + 875bf8c commit 6b11790

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+343
-2
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4 files changed

+343
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‎src/ProgressOnderwijsUtils.Analyzers/IfNotFalseAnalyzer.cs‎

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using System.Collections.Immutable;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.CSharp;
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using Microsoft.CodeAnalysis.CSharp.Syntax;
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using Microsoft.CodeAnalysis.Diagnostics;
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namespace ProgressOnderwijsUtils.Analyzers;
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[DiagnosticAnalyzer(LanguageNames.CSharp)]
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public sealed class IfNotFalseAnalyzer : DiagnosticAnalyzer
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{
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public static readonly DiagnosticDescriptor Rule = new(
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#pragma warning disable RS2008 // Enable analyzer release tracking - why would we care?
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"POU1004",
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#pragma warning restore RS2008 // Enable analyzer release tracking
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"Redundant if (!false) statement",
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"The if statement condition is always true (if (!false))",
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"CodeQuality",
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DiagnosticSeverity.Warning,
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true
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);
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public override ImmutableArray<DiagnosticDescriptor> SupportedDiagnostics
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=> [Rule,];
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public override void Initialize(AnalysisContext context)
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{
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context.ConfigureGeneratedCodeAnalysis(GeneratedCodeAnalysisFlags.None);
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context.EnableConcurrentExecution();
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context.RegisterSyntaxNodeAction(AnalyzeIfStatement, SyntaxKind.IfStatement);
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}
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private static void AnalyzeIfStatement(SyntaxNodeAnalysisContext context)
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{
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var ifStatement = (IfStatementSyntax)context.Node;
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if (ifStatement.Condition is PrefixUnaryExpressionSyntax prefix &&
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prefix.IsKind(SyntaxKind.LogicalNotExpression) &&
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prefix.Operand is LiteralExpressionSyntax literal &&
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literal.IsKind(SyntaxKind.FalseLiteralExpression)) {
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context.ReportDiagnostic(Diagnostic.Create(Rule, ifStatement.GetLocation()));
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}
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}
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}

‎src/ProgressOnderwijsUtils.Analyzers/IfNotFalseCodeFix.cs‎

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using System.Collections.Immutable;
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using System.Composition;
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using System.Linq;
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using System.Threading.Tasks;
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using Microsoft.CodeAnalysis;
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using Microsoft.CodeAnalysis.CodeActions;
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using Microsoft.CodeAnalysis.CodeFixes;
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using Microsoft.CodeAnalysis.CSharp.Syntax;
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using Microsoft.CodeAnalysis.Formatting;
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namespace ProgressOnderwijsUtils.Analyzers;
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[ExportCodeFixProvider(LanguageNames.CSharp, Name = nameof(IfNotFalseCodeFix))]
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[Shared]
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public sealed class IfNotFalseCodeFix : CodeFixProvider
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{
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public override ImmutableArray<string> FixableDiagnosticIds
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=> [IfNotFalseAnalyzer.Rule.Id,];
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public override FixAllProvider GetFixAllProvider()
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=> WellKnownFixAllProviders.BatchFixer;
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public override async Task RegisterCodeFixesAsync(CodeFixContext context)
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{
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const string title = "Remove redundant if statement";
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var diagnostic = context.Diagnostics.First();
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var root = await context.Document.GetSyntaxRootAsync(context.CancellationToken).ConfigureAwait(false);
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if (root is null) {
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return;
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}
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var ifStatement = root.FindNode(diagnostic.Location.SourceSpan).FirstAncestorOrSelf<IfStatementSyntax>();
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if (ifStatement is null) {
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return;
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}
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var newRoot = ifStatement.Statement is BlockSyntax { Statements.Count: > 0, } block
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? ReplaceWithBlockStatements(root, ifStatement, block)
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: root.RemoveNode(ifStatement, SyntaxRemoveOptions.KeepNoTrivia);
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if (newRoot is null) {
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return;
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}
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context.RegisterCodeFix(
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CodeAction.Create(
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title,
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_ => Task.FromResult(context.Document.WithSyntaxRoot(newRoot)),
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title
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),
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diagnostic
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);
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}
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static SyntaxNode ReplaceWithBlockStatements(SyntaxNode root, IfStatementSyntax ifStatement, BlockSyntax block)
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{
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var formattedStatements = block.Statements
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.Select(s => s.WithAdditionalAnnotations(Formatter.Annotation))
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.ToArray();
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return root.ReplaceNode(ifStatement, formattedStatements);
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}
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}

‎src/ProgressOnderwijsUtils.Analyzers/ProgressOnderwijsUtils.Analyzers.csproj‎

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<PropertyGroup>
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<Description>Bump dependencies</Description>
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<PackageTags>ProgressOnderwijs</PackageTags>
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<PackageReleaseNotes>Added (minimal) readme file</PackageReleaseNotes>
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<Version>2.1.5</Version>
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<PackageReleaseNotes>Added IfNotFalseAnalyzer</PackageReleaseNotes>
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<Version>2.1.6</Version>
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<TargetFramework>netstandard2.0</TargetFramework>
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<EnforceExtendedAnalyzerRules>true</EnforceExtendedAnalyzerRules>
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<PackageReadmeFile>readme.md</PackageReadmeFile>

‎test/ProgressOnderwijsUtils.Analyzers.Tests/IfNotFalseAnalyzerTest.cs‎

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using System.Linq;
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using System.Threading.Tasks;
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using ExpressionToCodeLib;
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using Microsoft.CodeAnalysis;
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using Xunit;
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namespace ProgressOnderwijsUtils.Analyzers.Tests;
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public sealed class IfNotFalseAnalyzerTests
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{
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[Fact]
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public void FlagsIfNotFalse()
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{
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var source = """
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class C
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{
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void M()
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{
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if (!false) { }
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}
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}
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""";
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var diagnostics = DiagnosticHelper.GetDiagnostics(new IfNotFalseAnalyzer(), source);
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PAssert.That(() => diagnostics.Single().Id == IfNotFalseAnalyzer.Rule.Id);
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PAssert.That(() => diagnostics.Single().Location.GetLineSpan().StartLinePosition.Line == 4);
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}
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[Fact]
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public void DoesNotFlagIfTrue()
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{
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var source = """
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class C
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{
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void M()
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{
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if (true) { }
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}
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}
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""";
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var diagnostics = DiagnosticHelper.GetDiagnostics(new IfNotFalseAnalyzer(), source);
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PAssert.That(() => diagnostics.None());
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}
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[Fact]
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public async Task CodeFix_RemovesIfNotFalse()
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{
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var testCases = new[] {
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false) { System.Console.WriteLine("Hello"); }
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("Hello");
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false) { System.Console.WriteLine("A"); System.Console.WriteLine("B"); }
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("A"); System.Console.WriteLine("B");
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false)
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{
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System.Console.WriteLine("Hello");
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}
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("Hello");
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false) { }
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false)
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{
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System.Console.WriteLine("A");
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System.Console.WriteLine("B");
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}
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("A");
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System.Console.WriteLine("B");
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false) { System.Console.WriteLine("A"); } else { System.Console.WriteLine("B"); }
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("A");
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false) { System.Console.WriteLine("A"); } else { System.Console.WriteLine("B"); }
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("A");
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}
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}
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""",
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},
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new {
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Source = """
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class C
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{
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void M()
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{
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if (!false)
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{
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System.Console.WriteLine("A");
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}
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else
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{
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System.Console.WriteLine("B");
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}
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}
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}
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""",
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Expected = """
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class C
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{
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void M()
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{
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System.Console.WriteLine("A");
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}
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}
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""",
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},
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};
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foreach (var test in testCases) {
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var workspace = DiagnosticHelper.CreateProjectWithTestFile(test.Source);
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var diagnostic = DiagnosticHelper.GetDiagnostics(new IfNotFalseAnalyzer(), workspace).Single(d => d.Id == IfNotFalseAnalyzer.Rule.Id); // otherwise we could get diagnostic like CS0162 (unreachable code)
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var fixesMade = await DiagnosticHelper.ApplyAllCodeFixes(workspace, diagnostic, new IfNotFalseCodeFix());
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PAssert.That(() => fixesMade == 1);
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var result = await workspace.CurrentSolution.Projects.Single().Documents.Single().GetTextAsync();
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var resultText = result.ToString().Replace("\r\n", "\n");
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Assert.Equal(test.Expected, resultText);
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}
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}
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}

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