Core(Tests): new rule and tests for it

Add a rule that suggest usage of auto-property for property
with getter that only returns some (immutable) value. Add
tests for it.

Co-authored-by: Mehrshad <[email protected]>

src/FSharpLint.Core/FSharpLint.Core.fsproj

@@ -51,6 +51,7 @@
     <Compile Include="Rules\Conventions\FavourReRaise.fs" />
     <Compile Include="Rules\Conventions\FavourConsistentThis.fs" />
     <Compile Include="Rules\Conventions\AvoidSinglePipeOperator.fs" />
+    <Compile Include="Rules\Conventions\SuggestUseAutoProperty.fs" />
     <Compile Include="Rules\Conventions\RaiseWithTooManyArguments\RaiseWithTooManyArgumentsHelper.fs" />
     <Compile Include="Rules\Conventions\RaiseWithTooManyArguments\FailwithWithSingleArgument.fs" />
     <Compile Include="Rules\Conventions\RaiseWithTooManyArguments\RaiseWithSingleArgument.fs" />

src/FSharpLint.Core/Rules/Conventions/SuggestUseAutoProperty.fs

@@ -0,0 +1,19 @@
+module FSharpLint.Rules.SuggestUseAutoProperty
+
+open System
+open FSharpLint.Framework
+open FSharpLint.Framework.Suggestion
+open FSharp.Compiler.Syntax
+open FSharpLint.Framework.Ast
+open FSharpLint.Framework.Rules
+
+let private runner (args: AstNodeRuleParams) =
+    failwith "Not yet implemented"
+
+let rule =
+    { Name = "SuggestUseAutoProperty"
+      Identifier = Identifiers.FavourConsistentThis
+      RuleConfig =
+        { AstNodeRuleConfig.Runner = runner
+          Cleanup = ignore } }
+    |> AstNodeRule

src/FSharpLint.Core/Rules/Identifiers.fs

@@ -82,3 +82,4 @@ let FavourConsistentThis = identifier 74
 let AvoidTooShortNames = identifier 75
 let FavourStaticEmptyFields = identifier 76
 let AvoidSinglePipeOperator = identifier 77
+let SuggestUseAutoProperty = identifier 78

src/FSharpLint.Core/Text.resx

@@ -349,3 +349,7 @@
     <value>Can use normal function call (instead of pipe operator) because there is no invocation chain (single invocation only).</value>
   </data>
 </root>
+  <data name="RulesSuggestUseAutoProperty" xml:space="preserve">
+    <value>Consider giving auto-properties via the "val" keyword</value>
+  </data>
+</root>

tests/FSharpLint.Core.Tests/FSharpLint.Core.Tests.fsproj

@@ -40,6 +40,7 @@
     <Compile Include="Rules\Conventions\FavourConsistentThis.fs" />
     <Compile Include="Rules\Conventions\AvoidTooShortNames.fs" />
     <Compile Include="Rules\Conventions\AvoidSinglePipeOperator.fs" />
+    <Compile Include="Rules\Conventions\SuggestUseAutoProperty.fs" />
     <Compile Include="Rules\Conventions\Naming\NamingHelpers.fs" />
     <Compile Include="Rules\Conventions\Naming\InterfaceNames.fs" />
     <Compile Include="Rules\Conventions\Naming\ExceptionNames.fs" />

tests/FSharpLint.Core.Tests/Rules/Conventions/SuggestUseAutoProperty.fs

@@ -0,0 +1,28 @@
+module FSharpLint.Core.Tests.Rules.Conventions.SuggestUseAutoProperty
+
+open NUnit.Framework
+open FSharpLint.Framework.Rules
+open FSharpLint.Rules
+
+[<TestFixture>]
+type TestSuggestUseAutoProperty() =
+    inherit TestAstNodeRuleBase.TestAstNodeRuleBase(SuggestUseAutoProperty.rule)
+
+    [<Test>]
+    member this.``Should suggest usage of auto-property for property that only returns immutable value`` () =
+        this.Parse """
+type Foo(content: int) =
+    member self.Content = content
+"""
+
+        Assert.IsTrue(this.ErrorsExist)
+
+    [<Test>]
+    member this.``Shouldn't suggest usage of auto-property for non-property member``() =
+        this.Parse """
+type Foo(content: int) =
+    member self.Content() = content
+"""
+
+        Assert.IsTrue(this.NoErrorsExist)
+