Inline type hints for F# (#14159)

vsintegration/src/FSharp.Editor/FSharp.Editor.fsproj

@@ -126,6 +126,9 @@
     <Compile Include="Build\SetGlobalPropertiesForSdkProjects.fs" />
     <Compile Include="AutomaticCompletion\BraceCompletionSessionProvider.fsi" />
     <Compile Include="AutomaticCompletion\BraceCompletionSessionProvider.fs" />
+    <Compile Include="Hints\HintService.fs" />
+    <Compile Include="Hints\NativeToRoslynHintConverter.fs" />
+    <Compile Include="Hints\RoslynAdapter.fs" />
     <Compile Include="Lens\LensDisplayService.fs" />
     <Compile Include="Lens\LensService.fs" />
     <Compile Include="Lens\LensProvider.fs" />

vsintegration/src/FSharp.Editor/Hints/HintService.fs

+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace Microsoft.VisualStudio.FSharp.Editor.Hints
+
+open Microsoft.CodeAnalysis
+open Microsoft.VisualStudio.FSharp.Editor
+open FSharp.Compiler.CodeAnalysis
+open FSharp.Compiler.Symbols
+open FSharp.Compiler.Text
+
+module HintService =
+
+    // Relatively convenient for testing
+    type NativeHint = {
+        Range: range
+        Parts: TaggedText list
+    }
+
+    let private isValidForHint 
+        (parseFileResults: FSharpParseFileResults) 
+        (symbol: FSharpMemberOrFunctionOrValue)
+        (symbolUse: FSharpSymbolUse) =
+        
+        let isNotAnnotatedManually = 
+            not (parseFileResults.IsTypeAnnotationGivenAtPosition symbolUse.Range.Start)
+
+        let isNotAfterDot = 
+            symbolUse.IsFromDefinition 
+            && not symbol.IsMemberThisValue
+
+        let isNotTypeAlias = 
+            not symbol.IsConstructorThisValue
+        
+        symbol.IsValue // we'll be adding other stuff gradually here
+        && isNotAnnotatedManually
+        && isNotAfterDot
+        && isNotTypeAlias
+
+    let private getHintParts
+        (symbol: FSharpMemberOrFunctionOrValue) 
+        (symbolUse: FSharpSymbolUse) =
+        
+        match symbol.GetReturnTypeLayout symbolUse.DisplayContext with
+        | Some typeInfo -> 
+            let colon = TaggedText(TextTag.Text, ": ")
+            colon :: (typeInfo |> Array.toList)
+        
+        // not sure when this can happen but better safe than sorry
+        | None -> 
+            []
+        
+    let private getHintsForSymbol parseResults (symbolUse: FSharpSymbolUse) =
+        match symbolUse.Symbol with
+        | :? FSharpMemberOrFunctionOrValue as mfvSymbol 
+          when isValidForHint parseResults mfvSymbol symbolUse ->
+            
+            [ {
+                Range = symbolUse.Range
+                Parts = getHintParts mfvSymbol symbolUse
+            } ]
+        
+        // we'll be adding other stuff gradually here
+        | _ -> 
+            []
+
+    let getHintsForDocument (document: Document) userOpName cancellationToken = 
+        async {
+            if isSignatureFile document.FilePath
+            then 
+                return []
+            else
+                let! parseResults, checkResults = 
+                    document.GetFSharpParseAndCheckResultsAsync userOpName 
+                
+                return 
+                    checkResults.GetAllUsesOfAllSymbolsInFile cancellationToken
+                    |> Seq.toList
+                    |> List.collect (getHintsForSymbol parseResults)
+        }

vsintegration/src/FSharp.Editor/Hints/NativeToRoslynHintConverter.fs

+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace Microsoft.VisualStudio.FSharp.Editor.Hints
+
+open System.Collections.Immutable
+open Microsoft.CodeAnalysis.Text
+open Microsoft.CodeAnalysis.ExternalAccess.FSharp.InlineHints
+open Microsoft.VisualStudio.FSharp.Editor
+open FSharp.Compiler.Text
+open HintService
+
+module NativeToRoslynHintConverter =
+
+    let rangeToSpan range sourceText = 
+        let symbolSpan = RoslynHelpers.FSharpRangeToTextSpan(sourceText, range)
+        let overshadowLength = 0 // anything >0 means overlaying the code
+        TextSpan(symbolSpan.End, overshadowLength)
+
+    let nativeToRoslynText (taggedText: TaggedText) = 
+        let tag = RoslynHelpers.roslynTag taggedText.Tag
+        let text = taggedText.Text
+        RoslynTaggedText(tag, text)
+
+    let convert sourceText hint =
+        let span = rangeToSpan hint.Range sourceText
+        let displayParts = hint.Parts |> Seq.map nativeToRoslynText
+        FSharpInlineHint(span, displayParts.ToImmutableArray())
\ No newline at end of file

vsintegration/src/FSharp.Editor/Hints/RoslynAdapter.fs

+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace Microsoft.VisualStudio.FSharp.Editor.Hints
+
+open System.Collections.Immutable
+open System.ComponentModel.Composition
+open Microsoft.CodeAnalysis.ExternalAccess.FSharp.InlineHints
+open Microsoft.VisualStudio.FSharp.Editor
+
+// So the Roslyn interface is called IFSharpInlineHintsService
+// but our implementation is called just HintsService.
+// That's because we'll likely use this API for things other than inline hints,
+// e.g. signature hints above the line, pipeline hints on the side and so on.
+
+[<Export(typeof<IFSharpInlineHintsService>)>]
+type internal RoslynAdapter 
+    [<ImportingConstructor>]
+    (settings: EditorOptions) =
+
+    static let userOpName = "Hints"
+
+    interface IFSharpInlineHintsService with
+        member _.GetInlineHintsAsync(document, _, cancellationToken) =
+            async {
+                if not settings.Advanced.IsInlineHintsEnabled 
+                then return ImmutableArray.Empty
+                
+                else
+                    let! sourceText = document.GetTextAsync cancellationToken |> Async.AwaitTask
+                    let! nativeHints = 
+                        HintService.getHintsForDocument document userOpName cancellationToken
+                
+                    let roslynHints = 
+                        nativeHints 
+                        |> Seq.map (NativeToRoslynHintConverter.convert sourceText)
+                
+                    return roslynHints.ToImmutableArray()
+            } |> RoslynHelpers.StartAsyncAsTask cancellationToken

vsintegration/src/FSharp.Editor/Options/EditorOptions.fs

@@ -85,10 +85,12 @@ type LensOptions =
 [<CLIMutable>]
 type AdvancedOptions =
     { IsBlockStructureEnabled: bool
-      IsOutliningEnabled: bool }
+      IsOutliningEnabled: bool
+      IsInlineHintsEnabled: bool }
     static member Default =
       { IsBlockStructureEnabled = true
-        IsOutliningEnabled = true }
+        IsOutliningEnabled = true
+        IsInlineHintsEnabled = false }
 
 [<CLIMutable>]
 type FormattingOptions =

vsintegration/src/FSharp.UIResources/AdvancedOptionsControl.xaml

@@ -24,6 +24,10 @@
                     <CheckBox x:Name="toggleOutloning" IsChecked="{Binding IsOutliningEnabled}"
                               Content="{x:Static local:Strings.Show_Outlining}"/>
                 </GroupBox>
+                <GroupBox Header="{x:Static local:Strings.Inline_Hints}">
+                    <CheckBox x:Name="toggleInlineHints" IsChecked="{Binding IsInlineHintsEnabled}"
+                              Content="{x:Static local:Strings.Show_Inline_Hints}"/>
+                </GroupBox>
             </StackPanel>
         </ScrollViewer>
     </Grid>

vsintegration/src/FSharp.UIResources/Strings.Designer.cs

@@ -204,6 +204,15 @@ public class Strings {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Inline Hints.
+        /// </summary>
+        public static string Inline_Hints {
+            get {
+                return ResourceManager.GetString("Inline_Hints", resourceCulture);
+            }
+        }
+
         /// <summary>
         ///   Looks up a localized string similar to IntelliSense Performance Options.
         /// </summary>
@@ -330,6 +339,15 @@ public class Strings {
             }
         }
         
+        /// <summary>
+        ///   Looks up a localized string similar to Display inline type hints (experimental).
+        /// </summary>
+        public static string Show_Inline_Hints {
+            get {
+                return ResourceManager.GetString("Show_Inline_Hints", resourceCulture);
+            }
+        }
+
         /// <summary>
         ///   Looks up a localized string similar to S_how navigation links as.
         /// </summary>

vsintegration/src/FSharp.UIResources/Strings.resx

@@ -189,6 +189,12 @@
   <data name="Show_Outlining" xml:space="preserve">
     <value>Show outlining and collapsible nodes for F# code</value>
   </data>
+  <data name="Inline_Hints" xml:space="preserve">
+    <value>Inline Hints</value>
+  </data>
+  <data name="Show_Inline_Hints" xml:space="preserve">
+    <value>Display inline type hints (experimental)</value>
+  </data>
   <data name="Time_until_stale_completion" xml:space="preserve">
     <value>Time until stale results are used (in milliseconds)</value>
   </data>

vsintegration/src/FSharp.UIResources/xlf/Strings.cs.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Vždy umístit otevřené příkazy na nejvyšší úroveň</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Zobrazit s_ymboly v neotevřených oborech názvů</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.de.xlf

@@ -7,6 +7,11 @@
         <target state="translated">open-Anweisungen immer an oberster Ebene platzieren</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">S_ymbole in nicht geöffneten Namespaces anzeigen</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.es.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Colocar siempre las instrucciones open en el nivel superior</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Mostrar sím_bolos en espacios de nombres sin abrir</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.fr.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Placer toujours les instructions open au niveau supérieur</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Afficher les sym_boles dans les espaces de noms non ouverts</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.it.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Inserisci sempre le istruzioni OPEN al primo livello</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Mostra si_mboli in spazi dei nomi non aperti</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.ja.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Open ステートメントを常に最上位に配置する</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">開かれていない名前空間の記号を表示する(_Y)</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.ko.xlf

@@ -7,6 +7,11 @@
         <target state="translated">항상 최상위에 open 문 배치</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">열려 있지 않은 네임스페이스에 기호 표시(_Y)</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.pl.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Zawsze umieszczaj otwarte instrukcje na najwyższym poziomie</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Pokaż s_ymbole w nieotwartych przestrzeniach nazw</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.pt-BR.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Sempre coloque as instruções abertas no nível superior</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Mostrar s_ímbolos em namespaces não abertos</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.ru.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Всегда располагайте открытые операторы на верхнем уровне</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">По_казать символы в неоткрытых пространствах имен</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.tr.xlf

@@ -7,6 +7,11 @@
         <target state="translated">Açık deyimleri her zaman en üst düzeye yerleştir</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">Açılmamış ad alanlarında s_embolleri göster</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.zh-Hans.xlf

@@ -7,6 +7,11 @@
         <target state="translated">始终在顶层放置 open 语句</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">显示未打开的命名空间中的符号(_Y)</target>

vsintegration/src/FSharp.UIResources/xlf/Strings.zh-Hant.xlf

@@ -7,6 +7,11 @@
         <target state="translated">一律將 open 陳述式放在最上層</target>
         <note />
       </trans-unit>
+      <trans-unit id="Inline_Hints">
+        <source>Inline Hints</source>
+        <target state="new">Inline Hints</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Lens">
         <source>Lens</source>
         <target state="translated">Lens</target>
@@ -77,6 +82,11 @@
         <target state="new">Parallelization (requires restart)</target>
         <note />
       </trans-unit>
+      <trans-unit id="Show_Inline_Hints">
+        <source>Display inline type hints (experimental)</source>
+        <target state="new">Display inline type hints (experimental)</target>
+        <note />
+      </trans-unit>
       <trans-unit id="Show_all_symbols">
         <source>Show s_ymbols in unopened namespaces</source>
         <target state="translated">顯示未開啟之命名空間中的符號(_Y)</target>

vsintegration/tests/UnitTests/HintServiceTests.fs

+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace VisualFSharp.UnitTests.Editor.Hints
+
+open NUnit.Framework
+open HintTestFramework
+
+module HintServiceTests =
+
+[<Test>]
+let ``Type hints are not shown in signature files`` () =
+    let fsiCode = """
+module Test
+
+val numbers: int[]
+"""
+    let fsCode = """
+module Test
+
+let numbers = [|42|]
+"""
+    let fsiDocument, _ = getFsiAndFsDocuments fsiCode fsCode
+
+    let result = getHints fsiDocument
+    
+    Assert.IsEmpty(result)
+
+[<Test>]
+let ``Type hints are not shown for let-bound functions yet`` () =
+    let code = """
+let setConsoleOut = System.Console.SetOut
+"""
+    let document = getFsDocument code
+
+    let result = getHints document
+
+    Assert.IsEmpty(result)
+
+[<Test>]
+let ``Type hint is shown for a let binding`` () =
+    let code = """
+type Song = { Artist: string; Title: string }
+
+let s = { Artist = "Moby"; Title = "Porcelain" }
+"""
+    let document = getFsDocument code
+    let expected = [{ Content = ": Song"; Location = (3, 6) }]
+
+    let actual = getHints document
+
+    Assert.AreEqual(expected, actual)
+
+[<Test>]
+let ``Type hint is not shown for a let binding when the type is manually specified`` () =
+    let code = """
+type Song = { Artist: string; Title: string }
+
+let s: Song = { Artist = "Moby"; Title = "Porcelain" }
+"""
+    let document = getFsDocument code
+    
+    let result = getHints document
+    
+    Assert.IsEmpty(result)
+
+[<Test>]
+let ``Type hint is shown for a parameter`` () =
+    let code = """
+type Song = { Artist: string; Title: string }
+
+let whoSings s = s.Artist
+"""
+    let document = getFsDocument code
+    let expected = [{ Content = ": Song"; Location = (3, 15) }]
+    
+    let actual = getHints document
+
+    Assert.AreEqual(expected, actual)
+
+[<Test>]
+let ``Type hint is not shown for a parameter when the type is manually specified`` () =
+    let code = """
+type Song = { Artist: string; Title: string }
+
+let whoSings (s: Song) = s.Artist
+"""
+    let document = getFsDocument code
+    
+    let result = getHints document
+    
+    Assert.IsEmpty(result)
+
+[<Test>] // here we don't want a hint after "this"
+let ``Type hint is not shown for type self-identifiers`` () =
+    let code = """
+type Song() =
+    member this.GetName() = "Porcelain"
+"""
+    let document = getFsDocument code
+    
+    let result = getHints document
+
+    Assert.IsEmpty(result)
+
+[<Test>] // here we don't want a hint after "x"
+let ``Type hint is not shown for type aliases`` () =
+    let code = """
+type Song() as x =
+    member this.Name = "Porcelain"
+"""
+    let document = getFsDocument code
+
+    let result = getHints document
+
+    Assert.IsEmpty(result)

vsintegration/tests/UnitTests/HintTestFramework.fs

+// Copyright (c) Microsoft Corporation.  All Rights Reserved.  See License.txt in the project root for license information.
+
+namespace VisualFSharp.UnitTests.Editor.Hints
+
+open System.Threading
+open Microsoft.VisualStudio.FSharp.Editor
+open Microsoft.VisualStudio.FSharp.Editor.Hints
+open Microsoft.VisualStudio.FSharp.Editor.Hints.HintService
+open VisualFSharp.UnitTests.Editor
+open Microsoft.CodeAnalysis.Text
+
+module HintTestFramework =
+
+// another representation for extra convenience
+type TestHint = {
+    Content: string
+    Location: int * int
+}
+
+let private convert hint = 
+    let content = 
+        hint.Parts
+        |> Seq.map (fun hintPart -> hintPart.Text)
+        |> String.concat ""
+
+    // that's about different coordinate systems
+    // in tests, the most convenient is the one used in editor,
+    // hence this conversion
+    let location = (hint.Range.StartLine - 1, hint.Range.EndColumn + 1)
+
+    { Content = content 
+      Location = location }
+
+let getFsDocument code = 
+    use project = SingleFileProject code
+    let fileName = fst project.Files.Head
+    let document, _ = RoslynTestHelpers.CreateSingleDocumentSolution(fileName, code)
+    document
+
+let getFsiAndFsDocuments (fsiCode: string) (fsCode: string) = 
+    RoslynTestHelpers.CreateTwoDocumentSolution(
+        "test.fsi",
+        SourceText.From fsiCode,
+        "test.fs",
+        SourceText.From fsCode)
+
+let getHints document = 
+    async {
+        let! hints = HintService.getHintsForDocument document "test" CancellationToken.None
+        return hints |> Seq.map convert
+    }
+    |> Async.RunSynchronously

vsintegration/tests/UnitTests/Tests.RoslynHelpers.fs

@@ -273,7 +273,59 @@ type RoslynTestHelpers private () =
 
         document
 
+    static member CreateTwoDocumentSolution (filePath1, text1: SourceText, filePath2, text2: SourceText) =
+        let workspace = new AdhocWorkspace(TestHostServices())
+
+        let projId = ProjectId.CreateNewId()
+        let docId1 = DocumentId.CreateNewId(projId)
+        let docId2 = DocumentId.CreateNewId(projId)
+
+        let docInfo1 =
+            DocumentInfo.Create(
+                docId1,
+                filePath1, 
+                loader=TextLoader.From(text1.Container, VersionStamp.Create(DateTime.UtcNow)),
+                filePath=filePath1,
+                sourceCodeKind= SourceCodeKind.Regular)
+
+        let docInfo2 =
+            DocumentInfo.Create(
+                docId2,
+                filePath2, 
+                loader=TextLoader.From(text2.Container, VersionStamp.Create(DateTime.UtcNow)),
+                filePath=filePath2,
+                sourceCodeKind= SourceCodeKind.Regular)
+
+        let projFilePath = "C:\\test.fsproj"
+        let projInfo =
+            ProjectInfo.Create(
+                projId,
+                VersionStamp.Create(DateTime.UtcNow),
+                projFilePath, 
+                "test.dll", 
+                LanguageNames.FSharp,
+                documents = [docInfo1;docInfo2],
+                filePath = projFilePath
+            )
+
+        let solutionInfo = SolutionInfo.Create(SolutionId.CreateNewId(), VersionStamp.Create(DateTime.UtcNow), "test.sln", [projInfo])
+        let solution = workspace.AddSolution(solutionInfo)
+
+        workspace
+            .Services
+            .GetService<IFSharpWorkspaceService>()
+            .FSharpProjectOptionsManager
+            .SetCommandLineOptions(projId, [|filePath1;filePath2|], ImmutableArray.Empty)
+
+        let document1 = solution.GetProject(projId).GetDocument(docId1)
+        let document2 = solution.GetProject(projId).GetDocument(docId2)
+        document1, document2
+
     static member CreateSingleDocumentSolution (filePath, code: string, ?options) =
         let text = SourceText.From(code)
         RoslynTestHelpers.CreateSingleDocumentSolution(filePath, text, ?options = options), text
 
+    static member CreateTwoDocumentSolution (filePath1, code1: string, filePath2, code2: string) =
+        let text1 = SourceText.From code1
+        let text2 = SourceText.From code2
+        RoslynTestHelpers.CreateTwoDocumentSolution(filePath1, text1, filePath2, text2)

vsintegration/tests/UnitTests/VisualFSharp.UnitTests.fsproj

@@ -102,6 +102,12 @@
     <Compile Include="QuickInfoTests.fs">
       <Link>Editor\QuickInfoTests.fs</Link>
     </Compile>
+    <Compile Include="HintTestFramework.fs">
+      <Link>Editor\Hints\HintTestFramework.fs</Link>
+    </Compile>
+    <Compile Include="HintServiceTests.fs">
+      <Link>Editor\Hints\HintServiceTests.fs</Link>
+    </Compile>
     <Compile Include="GoToDefinitionServiceTests.fs">
       <Link>Editor\GoToDefinitionServiceTests.fs</Link>
     </Compile>