test: fix tests failing to import other virtual files

Author: JasonWeinzierl

tests/etc/could-be-type.test.ts

@@ -106,11 +106,10 @@ describe('couldBeType', () => {
     expect(couldBeType(type, 'B')).toBe(true);
   });
 
-  it.todo('should support fully-qualified types', () => {
-    // TODO: This test is disabled because we're failing to import from other files using @typescript/vfs.  See env.languageService.getSemanticDiagnostics(fileName) for error message.
+  it('should support fully-qualified types', () => {
     const { sourceFile, typeChecker } = createSourceFileAndTypeChecker(
       `
-      import { A } from "./a";
+      import { A } from "/a";
       class B {}
       let a: A;
       let b: B;
@@ -123,13 +122,13 @@ describe('couldBeType', () => {
 
     expect(
       couldBeType(typeA, 'A', {
-        name: /"a"/,
+        name: /"\/a"/,
         typeChecker,
       }),
     ).toBe(true);
     expect(
       couldBeType(typeB, 'B', {
-        name: /"b"/,
+        name: /b/,
         typeChecker,
       }),
     ).toBe(false);

tests/etc/create-source-file-and-type-checker.ts

@@ -18,13 +18,13 @@ export function createSourceFileAndTypeChecker(
 
   const fsMap = tsvfs.createDefaultMapFromNodeModules(compilerOptions, ts);
   fsMap.set(fileName, sourceText);
-  fsMap.set('a.ts', 'export class A {}');
-  fsMap.set('b.ts', 'export class B {}');
+  fsMap.set('/a.ts', 'export class A {}');
+  fsMap.set('/b.ts', 'export class B {}');
 
   const system = tsvfs.createSystem(fsMap);
   const env = tsvfs.createVirtualTypeScriptEnvironment(
     system,
-    [fileName, 'a.ts', 'b.ts'],
+    [fileName, '/a.ts', '/b.ts'],
     ts,
     compilerOptions,
   );
@@ -33,6 +33,11 @@ export function createSourceFileAndTypeChecker(
   if (program === undefined) {
     throw new Error('Failed to get program');
   }
+  // Note: If you're having trouble with vfs, run the tests with DEBUG=1 for more output.
+  const fileIssues = env.languageService.getSemanticDiagnostics(fileName);
+  if (fileIssues.length) {
+    throw new Error(fileIssues.map(diag => diag.messageText).join());
+  }
 
   return {
     // eslint-disable-next-line @typescript-eslint/no-non-null-assertion