Replace fourslash test with proper tsc test that reproduces the bug

Co-authored-by: andrewbranch <3277153+andrewbranch@users.noreply.github.com>

Author: Copilot

src/testRunner/unittests/tsc/projectReferences.ts

@@ -90,6 +90,35 @@ describe("unittests:: tsc:: projectReferences::", () => {
         commandLineArgs: ["--p", "app", "--pretty", "false"],
     });
 
+    verifyTsc({
+        scenario: "projectReferences",
+        subScenario: "referenced project with esnext module disallows synthetic default imports",
+        sys: () =>
+            TestServerHost.createWatchedSystem({
+                "/home/src/workspaces/project/lib/tsconfig.json": jsonToReadableText({
+                    compilerOptions: {
+                        composite: true,
+                        declaration: true,
+                        module: "esnext",
+                        moduleResolution: "bundler",
+                    },
+                }),
+                "/home/src/workspaces/project/lib/utils.ts": "export const test = () => 'test';",
+                "/home/src/workspaces/project/lib/utils.d.ts": "export declare const test: () => string;",
+                "/home/src/workspaces/project/app/tsconfig.json": jsonToReadableText({
+                    compilerOptions: {
+                        module: "esnext",
+                        moduleResolution: "bundler",
+                    },
+                    references: [
+                        { path: "../lib" },
+                    ],
+                }),
+                "/home/src/workspaces/project/app/index.ts": `import Test from '../lib/utils';\nconsole.log(Test.test());`,
+            }),
+        commandLineArgs: ["--p", "app", "--pretty", "false"],
+    });
+
     verifyTsc({
         scenario: "projectReferences",
         subScenario: "referencing ambient const enum from referenced project with preserveConstEnums",

tests/baselines/reference/tsc/projectReferences/referenced-project-with-esnext-module-disallows-synthetic-default-imports.js

@@ -0,0 +1,62 @@
+currentDirectory:: /home/src/workspaces/project useCaseSensitiveFileNames:: false
+Input::
+//// [/home/src/workspaces/project/lib/tsconfig.json]
+{
+  "compilerOptions": {
+    "composite": true,
+    "declaration": true,
+    "module": "esnext",
+    "moduleResolution": "bundler"
+  }
+}
+
+//// [/home/src/workspaces/project/lib/utils.ts]
+export const test = () => 'test';
+
+//// [/home/src/workspaces/project/lib/utils.d.ts]
+export declare const test: () => string;
+
+//// [/home/src/workspaces/project/app/tsconfig.json]
+{
+  "compilerOptions": {
+    "module": "esnext",
+    "moduleResolution": "bundler"
+  },
+  "references": [
+    {
+      "path": "../lib"
+    }
+  ]
+}
+
+//// [/home/src/workspaces/project/app/index.ts]
+import Test from '../lib/utils';
+console.log(Test.test());
+
+//// [/home/src/tslibs/TS/Lib/lib.d.ts]
+interface Boolean {}
+interface Function {}
+interface CallableFunction {}
+interface NewableFunction {}
+interface IArguments {}
+interface Number { toExponential: any; }
+interface Object {}
+interface RegExp {}
+interface String { charAt: any; }
+interface Array<T> { length: number; [n: number]: T; }
+interface ReadonlyArray<T> {}
+declare const console: { log(msg: any): void; };
+
+
+/home/src/tslibs/TS/Lib/tsc.js --p app --pretty false
+Output::
+app/index.ts(1,8): error TS1192: Module '"/home/src/workspaces/project/lib/utils"' has no default export.
+
+
+//// [/home/src/workspaces/project/app/index.js]
+import Test from '../lib/utils';
+console.log(Test.test());
+
+
+
+exitCode:: ExitStatus.DiagnosticsPresent_OutputsGenerated