Test refactoring, utilities (#459)

* Factored out BCL refs

* Update TestUtilities.cs

* BCL and compiling code tests mostly rewritten with utils

* E2e almost done

* Scripting fixed

* Update CodeCompletionTests.cs

* Factored out and simplified completion and signature service tests

* Update FlowAnalysisTests.cs

* Update LocalFunctionsTests.cs

* Update OverloadingTests.cs

* More work

* Update TypeCheckingTests.cs

* Update SyntaxHighlighterTests.cs

* More

* Compiles

* Update TestUtilities.cs

* Update TestUtilities.cs

* Update TestUtilities.cs

* All fixed

* Final fix

* Compiles again

* Smartened up completion

* Update DracoLanguageServer.cs

* Cleanup

* Fix

src/Draco.Compiler.Tests/EndToEnd/Issue139Tests.cs

@@ -1,7 +1,5 @@
-using System.Collections.Immutable;
-using Draco.Compiler.Api;
-using Draco.Compiler.Api.Syntax;
 using Draco.Compiler.Internal.Declarations;
+using static Draco.Compiler.Tests.TestUtilities;
 
 namespace Draco.Compiler.Tests.EndToEnd;
 
@@ -201,14 +199,9 @@ func foo(): ImmutableArray { }
     [Theory]
     public void DoesNotCrash(string source)
     {
-        var syntaxTree = SyntaxTree.Parse(source);
-        var compilation = Compilation.Create(
-            syntaxTrees: [syntaxTree],
-            metadataReferences: Basic.Reference.Assemblies.Net80.ReferenceInfos.All
-                .Select(r => MetadataReference.FromPeStream(new MemoryStream(r.ImageBytes)))
-                .ToImmutableArray());
-        _ = compilation.Diagnostics.ToList();
-        compilation.Emit(peStream: new MemoryStream());
+        var peStream = new MemoryStream();
+        var compilation = CreateCompilation(source);
+        _ = compilation.Emit(peStream);
     }
 
     [Fact]

src/Draco.Compiler.Tests/EndToEnd/MetadataTests.cs

@@ -1,20 +1,21 @@
 using System.Reflection;
 using System.Reflection.Metadata;
 using System.Reflection.PortableExecutable;
+using static Draco.Compiler.Tests.TestUtilities;
 
 namespace Draco.Compiler.Tests.EndToEnd;
 
-public sealed class MetadataTests : EndToEndTestsBase
+public sealed class MetadataTests
 {
     [Fact]
     public void TestReferencedAssemblyVersion()
     {
-        using var assemblyBytes = CompileRaw("""
+        using var assemblyBytes = CompileToMemory(CreateCompilation("""
             import System.Console;
             func main() {
                 WriteLine();
             }
-            """);
+            """));
 
         using var peReader = new PEReader(assemblyBytes);
         var metadataReader = peReader.GetMetadataReader();

src/Draco.Compiler.Tests/Scripting/ReplSessionTests.cs

@@ -1,14 +1,10 @@
-using Draco.Compiler.Api;
 using Draco.Compiler.Api.Scripting;
-using static Basic.Reference.Assemblies.Net80;
+using static Draco.Compiler.Tests.TestUtilities;
 
 namespace Draco.Compiler.Tests.Scripting;
 
 public sealed class ReplSessionTests
 {
-    private static IEnumerable<MetadataReference> BclReferences => ReferenceInfos.All
-        .Select(r => MetadataReference.FromPeStream(new MemoryStream(r.ImageBytes)));
-
     [InlineData("", null)]
     [InlineData("// hello", null)]
     [InlineData("1 + 2", 3)]
@@ -19,7 +15,7 @@ public sealed class ReplSessionTests
     [Theory]
     public void BasicExpressions(string input, object? output)
     {
-        var replSession = new ReplSession([.. BclReferences]);
+        var replSession = new ReplSession(BclReferences);
 
         var result = replSession.Evaluate(input);
 
@@ -31,7 +27,7 @@ public void BasicExpressions(string input, object? output)
     [Theory]
     public void InvalidEntries(string input)
     {
-        var replSession = new ReplSession([.. BclReferences]);
+        var replSession = new ReplSession(BclReferences);
 
         var result = replSession.Evaluate(input);
 
@@ -92,7 +88,7 @@ private static void AssertSequence(params (string Code, object? Value)[] pairs)
 
     private static IEnumerable<ExecutionResult<object?>> ExecuteSequence(IEnumerable<string> inputs)
     {
-        var replSession = new ReplSession([.. BclReferences]);
+        var replSession = new ReplSession(BclReferences);
 
         var ms = new MemoryStream();
         var reader = new StreamReader(ms);

src/Draco.Compiler.Tests/Scripting/ScriptTests.cs

@@ -1,6 +1,5 @@
-using System.Collections.Immutable;
-using Draco.Compiler.Api;
 using Draco.Compiler.Api.Scripting;
+using static Draco.Compiler.Tests.TestUtilities;
 
 namespace Draco.Compiler.Tests.Scripting;
 
@@ -15,10 +14,7 @@ public void BasicAssignmentAndAddition()
             var y = 4;
             x + y
             """,
-            // TODO: We could factor out BCL refs into some global, we repeat this LINQ a lot in tests
-            metadataReferences: Basic.Reference.Assemblies.Net80.ReferenceInfos.All
-                .Select(r => MetadataReference.FromPeStream(new MemoryStream(r.ImageBytes)))
-                .ToImmutableArray());
+            metadataReferences: BclReferences);
 
         // Act
         var result = script.Execute();
@@ -35,9 +31,7 @@ public void SyntaxErrorInScript()
         var script = Script.Create<int>("""
             var x = ;
             """,
-            metadataReferences: Basic.Reference.Assemblies.Net80.ReferenceInfos.All
-                .Select(r => MetadataReference.FromPeStream(new MemoryStream(r.ImageBytes)))
-                .ToImmutableArray());
+            metadataReferences: BclReferences);
 
         // Act
         var result = script.Execute();