Centralize Visual Studio installation discovery and assembly resolution in test infrastructure

tests/FSharp.Test.Utilities/FSharp.Test.Utilities.fsproj

@@ -102,7 +102,8 @@
     <PackageReference Include="System.Diagnostics.DiagnosticSource" Version="$(SystemDiagnosticsDiagnosticSourceVersion)" />
   </ItemGroup>
 <PropertyGroup>
- <NoWarn>$(NoWarn);NU1510</NoWarn> <!-- NU1510: Project is explicitly referencing the runtime assembly 'System.Collections.Immutable', however, if we remove it, it tries to find it on the wrong path. Also, local NoWarn does not help - This is just me trying to enforce it -->
+ <NoWarn>$(NoWarn);NU1510;44</NoWarn> <!-- NU1510: Project is explicitly referencing the runtime assembly 'System.Collections.Immutable', however, if we remove it, it tries to find it on the wrong path. Also, local NoWarn does not help - This is just me trying to enforce it -->
+ <!-- 44: AssemblyName.CodeBase is deprecated but needed for assembly resolution in VS integration tests -->
 </PropertyGroup>
   <ItemGroup>
     <PackageReference Include="System.Collections.Immutable" Version="$(SystemCollectionsImmutableVersion)" GeneratePathProperty="true"  />

tests/FSharp.Test.Utilities/VSInstallDiscovery.fs

@@ -126,3 +126,55 @@ module VSInstallDiscovery =
         | NotFound reason -> 
             logAction $"Visual Studio installation not found: {reason}"
             None
+
+    /// Gets the VS installation directory or fails with a detailed error message.
+    /// This is the recommended method for test scenarios that require VS to be installed.
+    let getVSInstallDirOrFail () : string =
+        match tryFindVSInstallation () with
+        | Found (path, _) -> path
+        | NotFound reason -> 
+            failwith $"Visual Studio installation not found: {reason}. Ensure VS is installed or environment variables (VSAPPIDDIR, VS*COMNTOOLS) are set."
+
+/// Assembly resolver for Visual Studio test infrastructure.
+/// Provides centralized assembly resolution for VS integration tests.
+module VSAssemblyResolver =
+    open System
+    open System.IO
+    open System.Reflection
+    open System.Globalization
+
+    /// Adds an assembly resolver that probes Visual Studio installation directories.
+    /// This should be called early in test initialization to ensure VS assemblies can be loaded.
+    let addResolver () =
+        let vsInstallDir = VSInstallDiscovery.getVSInstallDirOrFail ()
+
+        let probingPaths =
+            [|
+                Path.Combine(vsInstallDir, @"IDE\CommonExtensions\Microsoft\Editor")
+                Path.Combine(vsInstallDir, @"IDE\PublicAssemblies")
+                Path.Combine(vsInstallDir, @"IDE\PrivateAssemblies")
+                Path.Combine(vsInstallDir, @"IDE\CommonExtensions\Microsoft\ManagedLanguages\VBCSharp\LanguageServices")
+                Path.Combine(vsInstallDir, @"IDE\Extensions\Microsoft\CodeSense\Framework")
+                Path.Combine(vsInstallDir, @"IDE")
+            |]
+
+        AppDomain.CurrentDomain.add_AssemblyResolve(fun _ args ->
+            let found () =
+                probingPaths
+                |> Seq.tryPick (fun p ->
+                    try
+                        let name = AssemblyName(args.Name)
+                        let codebase = Path.GetFullPath(Path.Combine(p, name.Name) + ".dll")
+                        if File.Exists(codebase) then
+                            name.CodeBase <- codebase
+                            name.CultureInfo <- Unchecked.defaultof<CultureInfo>
+                            name.Version <- Unchecked.defaultof<Version>
+                            Some name
+                        else
+                            None
+                    with _ ->
+                        None)
+
+            match found () with
+            | None -> Unchecked.defaultof<Assembly>
+            | Some name -> Assembly.Load(name))

vsintegration/tests/FSharp.Editor.Tests/Helpers/AssemblyResolver.fs

@@ -2,62 +2,9 @@
 
 namespace FSharp.Editor.Tests.Helpers
 
-open System
-open System.IO
-open System.Reflection
-
 module AssemblyResolver =
-    open System.Globalization
-    open FSharp.Test.VSInstallDiscovery
-
-    let vsInstallDir =
-        // Use centralized VS installation discovery with graceful fallback
-        match tryGetVSInstallDir () with
-        | Some dir -> dir
-        | None ->
-            // Fallback to legacy behavior for backward compatibility
-            let vsvar =
-                let var = Environment.GetEnvironmentVariable("VS170COMNTOOLS")
-
-                if String.IsNullOrEmpty var then
-                    Environment.GetEnvironmentVariable("VSAPPIDDIR")
-                else
-                    var
-
-            if String.IsNullOrEmpty vsvar then
-                failwith "VS170COMNTOOLS and VSAPPIDDIR environment variables not found."
-
-            Path.Combine(vsvar, "..")
-
-    let probingPaths =
-        [|
-            Path.Combine(vsInstallDir, @"IDE\CommonExtensions\Microsoft\Editor")
-            Path.Combine(vsInstallDir, @"IDE\PublicAssemblies")
-            Path.Combine(vsInstallDir, @"IDE\PrivateAssemblies")
-            Path.Combine(vsInstallDir, @"IDE\CommonExtensions\Microsoft\ManagedLanguages\VBCSharp\LanguageServices")
-            Path.Combine(vsInstallDir, @"IDE\Extensions\Microsoft\CodeSense\Framework")
-            Path.Combine(vsInstallDir, @"IDE")
-        |]
-
-    let addResolver () =
-        AppDomain.CurrentDomain.add_AssemblyResolve (fun h args ->
-            let found () =
-                (probingPaths)
-                |> Seq.tryPick (fun p ->
-                    try
-                        let name = AssemblyName(args.Name)
-                        let codebase = Path.GetFullPath(Path.Combine(p, name.Name) + ".dll")
-
-                        if File.Exists(codebase) then
-                            name.CodeBase <- codebase
-                            name.CultureInfo <- Unchecked.defaultof<CultureInfo>
-                            name.Version <- Unchecked.defaultof<Version>
-                            Some(name)
-                        else
-                            None
-                    with _ ->
-                        None)
+    open FSharp.Test.VSAssemblyResolver
 
-            match found () with
-            | None -> Unchecked.defaultof<Assembly>
-            | Some name -> Assembly.Load(name))
+    /// Adds an assembly resolver that probes Visual Studio installation directories.
+    /// This is a compatibility shim that delegates to the centralized implementation.
+    let addResolver = addResolver

vsintegration/tests/Salsa/VisualFSharp.Salsa.fsproj

@@ -24,6 +24,9 @@
     <Compile Include="..\unittests\TestLib.Utils.fs">
       <Link>UnitTests.TestLib.Utils.fs</Link>
     </Compile>
+    <Compile Include="..\..\..\tests\FSharp.Test.Utilities\VSInstallDiscovery.fs">
+      <Link>VSInstallDiscovery.fs</Link>
+    </Compile>
     <Compile Include="FSharpLanguageServiceTestable.fs" />
     <Compile Include="VsMocks.fs" />
     <Compile Include="Salsa.fs" />

vsintegration/tests/Salsa/VsMocks.fs

@@ -1642,6 +1642,7 @@ module internal VsActual =
     open System.ComponentModel.Composition.Primitives
     open Microsoft.VisualStudio.Text
     open Microsoft.VisualStudio.Threading
+    open FSharp.Test.VSInstallDiscovery
 
     type TestExportJoinableTaskContext () =
 
@@ -1650,22 +1651,7 @@ module internal VsActual =
         [<System.ComponentModel.Composition.Export(typeof<JoinableTaskContext>)>]
         member public _.JoinableTaskContext : JoinableTaskContext = jtc
 
-    let vsInstallDir =
-        // use the environment variable to find the VS installdir
-        let vsvar =
-            // Try VS180COMNTOOLS first, then VS170COMNTOOLS, then VSAPPIDDIR
-            // TODO : use tryGetVSInstallDir from test utils instead
-            let var18 = Environment.GetEnvironmentVariable("VS180COMNTOOLS")
-            if String.IsNullOrEmpty var18 then
-                let var17 = Environment.GetEnvironmentVariable("VS170COMNTOOLS")
-                if String.IsNullOrEmpty var17 then
-                    Environment.GetEnvironmentVariable("VSAPPIDDIR")
-                else
-                    var17
-            else
-                var18
-        if String.IsNullOrEmpty vsvar then failwith "VS180COMNTOOLS, VS170COMNTOOLS and VSAPPIDDIR environment variables not found."
-        Path.Combine(vsvar, "..")
+    let vsInstallDir = getVSInstallDirOrFail ()
 
     let CreateEditorCatalog() =
         let thisAssembly = Assembly.GetExecutingAssembly().Location

vsintegration/tests/UnitTests/AssemblyResolver.fs

@@ -1,52 +1,8 @@
 namespace Microsoft.VisualStudio.FSharp
 
-open System
-open System.IO
-open System.Reflection
-
 module AssemblyResolver =
-    open System.Globalization
-    open FSharp.Test.VSInstallDiscovery
-
-    let vsInstallDir =
-        // Use centralized VS installation discovery with graceful fallback
-        match tryGetVSInstallDir () with
-        | Some dir -> dir
-        | None -> 
-            // Fallback to legacy behavior for backward compatibility
-            let vsvar =
-                let var = Environment.GetEnvironmentVariable("VS170COMNTOOLS")
-                if String.IsNullOrEmpty var then
-                    Environment.GetEnvironmentVariable("VSAPPIDDIR")
-                else
-                    var
-            if String.IsNullOrEmpty vsvar then failwith "VS170COMNTOOLS and VSAPPIDDIR environment variables not found."
-            Path.Combine(vsvar, "..")
-
-    let probingPaths = [|
-        Path.Combine(vsInstallDir, @"IDE\CommonExtensions\Microsoft\Editor")
-        Path.Combine(vsInstallDir, @"IDE\PublicAssemblies")
-        Path.Combine(vsInstallDir, @"IDE\PrivateAssemblies")
-        Path.Combine(vsInstallDir, @"IDE\CommonExtensions\Microsoft\ManagedLanguages\VBCSharp\LanguageServices")
-        Path.Combine(vsInstallDir, @"IDE\Extensions\Microsoft\CodeSense\Framework")
-        Path.Combine(vsInstallDir, @"IDE")
-    |]
+    open FSharp.Test.VSAssemblyResolver
 
-    let addResolver () =
-        AppDomain.CurrentDomain.add_AssemblyResolve(fun h args ->
-            let found () =
-                (probingPaths ) |> Seq.tryPick(fun p ->
-                    try
-                        let name = AssemblyName(args.Name)
-                        let codebase = Path.GetFullPath(Path.Combine(p, name.Name) + ".dll")
-                        if File.Exists(codebase) then
-                            name.CodeBase <- codebase
-                            name.CultureInfo <- Unchecked.defaultof<CultureInfo>
-                            name.Version <- Unchecked.defaultof<Version>
-                            Some (name)
-                        else None
-                    with | _ -> None
-                    )
-            match found() with
-            | None -> Unchecked.defaultof<Assembly>
-            | Some name -> Assembly.Load(name) )
+    /// Adds an assembly resolver that probes Visual Studio installation directories.
+    /// This is a compatibility shim that delegates to the centralized implementation.
+    let addResolver = addResolver