Fix test harness bugs hidden by method behavior (#55723)

Author: jakebailey

src/harness/fakesHosts.ts

@@ -350,7 +350,7 @@ export class CompilerHost implements ts.CompilerHost {
         return vpath.resolve(this.getDefaultLibLocation(), ts.getDefaultLibFileName(options));
     }
 
-    public getSourceFile(fileName: string, languageVersion: number): ts.SourceFile | undefined {
+    public getSourceFile(fileName: string, languageVersionOrOptions: ts.ScriptTarget | ts.CreateSourceFileOptions): ts.SourceFile | undefined {
         const canonicalFileName = this.getCanonicalFileName(vpath.resolve(this.getCurrentDirectory(), fileName));
         const existing = this._sourceFiles.get(canonicalFileName);
         if (existing) return existing;
@@ -364,7 +364,7 @@ export class CompilerHost implements ts.CompilerHost {
         // reused across multiple tests. In that case, we cache the SourceFile we parse
         // so that it can be reused across multiple tests to avoid the cost of
         // repeatedly parsing the same file over and over (such as lib.d.ts).
-        const cacheKey = this.vfs.shadowRoot && `SourceFile[languageVersion=${languageVersion},setParentNodes=${this._setParentNodes}]`;
+        const cacheKey = this.vfs.shadowRoot && `SourceFile[languageVersionOrOptions=${languageVersionOrOptions !== undefined ? JSON.stringify(languageVersionOrOptions) : undefined},setParentNodes=${this._setParentNodes}]`;
         if (cacheKey) {
             const meta = this.vfs.filemeta(canonicalFileName);
             const sourceFileFromMetadata = meta.get(cacheKey) as ts.SourceFile | undefined;
@@ -374,7 +374,7 @@ export class CompilerHost implements ts.CompilerHost {
             }
         }
 
-        const parsed = ts.createSourceFile(fileName, content, languageVersion, this._setParentNodes || this.shouldAssertInvariants);
+        const parsed = ts.createSourceFile(fileName, content, languageVersionOrOptions, this._setParentNodes || this.shouldAssertInvariants);
         if (this.shouldAssertInvariants) {
             Utils.assertInvariants(parsed, /*parent*/ undefined);
         }

src/harness/harnessIO.ts

@@ -243,13 +243,13 @@ export namespace Compiler {
     export function createSourceFileAndAssertInvariants(
         fileName: string,
         sourceText: string,
-        languageVersion: ts.ScriptTarget,
+        languageVersionOrOptions: ts.ScriptTarget | ts.CreateSourceFileOptions,
     ) {
         // We'll only assert invariants outside of light mode.
         const shouldAssertInvariants = !lightMode;
 
         // Only set the parent nodes if we're asserting invariants.  We don't need them otherwise.
-        const result = ts.createSourceFile(fileName, sourceText, languageVersion, /*setParentNodes:*/ shouldAssertInvariants);
+        const result = ts.createSourceFile(fileName, sourceText, languageVersionOrOptions, /*setParentNodes:*/ shouldAssertInvariants);
 
         if (shouldAssertInvariants) {
             Utils.assertInvariants(result, /*parent:*/ undefined);