Simplify LINQ

ChangeLog.md

@@ -11,6 +11,9 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 - Add analyzer "Use raw string literal" [RCS1266](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1266) ([PR](https://github.com/dotnet/roslynator/pull/1375))
 - Add analyzer "Convert 'string.Concat' to interpolated string" [RCS1267](https://josefpihrt.github.io/docs/roslynator/analyzers/RCS1267) ([PR](https://github.com/dotnet/roslynator/pull/1379))
+- Simplify LINQ query [RCS1077](https://josefpihrt.github.io/docs/roslynator/analyzers/1077) ([PR](https://github.com/dotnet/roslynator/pull/1384))
+ - `items.Select(selector).Average()` => `items.Average(selector)`
+ - `items.Select(selector).Sum()` => `items.Sum(selector)`
 
 ## [4.10.0] - 2024-01-24
 

src/Analyzers/CSharp/Analysis/InvocationExpressionAnalyzer.cs

@@ -134,11 +134,13 @@ private static void AnalyzeInvocationExpression(SyntaxNodeAnalysisContext contex
 
  break;
  }
+ case "Average":
  case "Max":
  case "Min":
+ case "Sum":
  {
  if (DiagnosticRules.OptimizeLinqMethodCall.IsEffective(context))
- OptimizeLinqMethodCallAnalysis.AnalyzeSelectAndMinOrMax(context, invocationInfo);
+ OptimizeLinqMethodCallAnalysis.AnalyzeSelectAndAverageOrMinOrMaxOrSum(context, invocationInfo);
 
  break;
  }

src/Analyzers/CSharp/Analysis/OptimizeLinqMethodCallAnalysis.cs

@@ -107,8 +107,8 @@ public static void AnalyzeWhere(SyntaxNodeAnalysisContext context, in SimpleMemb
  Properties.SimplifyLinqMethodChain);
  }
 
- // items.Select(selector).Min/Max() >>> items.Min/Max(selector)
- public static void AnalyzeSelectAndMinOrMax(
+ // items.Select(selector).Average/Min/Max/Sum() >>> items.Average/Min/Max/Sum(selector)
+ public static void AnalyzeSelectAndAverageOrMinOrMaxOrSum(
  SyntaxNodeAnalysisContext context,
  in SimpleMemberInvocationExpressionInfo invocationInfo)
  {

src/Tests/Analyzers.Tests/RCS1077OptimizeLinqMethodCallTests.cs

@@ -180,6 +180,58 @@ void M()
 ");
  }
 
+ [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
+ public async Task Test_SelectAndAverage()
+ {
+ await VerifyDiagnosticAndFixAsync(@"
+using System.Linq;
+
+class C
+{
+ void M()
+ {
+ double max = Enumerable.Empty<int>().[|Select(f => f).Average()|];
+ }
+}
+", @"
+using System.Linq;
+
+class C
+{
+ void M()
+ {
+ double max = Enumerable.Empty<int>().Average(f => f);
+ }
+}
+");
+ }
+
+ [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
+ public async Task Test_SelectAndSum()
+ {
+ await VerifyDiagnosticAndFixAsync(@"
+using System.Linq;
+
+class C
+{
+ void M()
+ {
+ int max = Enumerable.Empty<int>().[|Select(f => f).Sum()|];
+ }
+}
+", @"
+using System.Linq;
+
+class C
+{
+ void M()
+ {
+ int max = Enumerable.Empty<int>().Sum(f => f);
+ }
+}
+");
+ }
+
  [Fact, Trait(Traits.Analyzer, DiagnosticIdentifiers.OptimizeLinqMethodCall)]
  public async Task Test_SelectAndMin_ImmutableArray()
  {