test(mobile): refuse an unlisted native package by the member a mount reads

Both emitted interop helpers short-circuit on `__esModule`, so answering `true`
hands the refusing trap back unwrapped to `__importDefault` and `__importStar`.
All three import forms now load the importer and throw the named refusal at the
first member read, instead of a namespace import silently yielding `undefined`
and failing later at the call.

Claude-Session: https://claude.ai/code/session_01JNnE9qzUZMMnqpZWCqM3nb

mobile/src/test-support/rpc-recording/operation-module-loader.test.ts

@@ -54,11 +54,11 @@ describe('the mounted module loader', () => {
   })
 
   /**
-   * `__importDefault` reads `__esModule` before any member, so refusing it kills a default import of
-   * an unlisted package at module load — before the recording can show which member was wanted, and
-   * for modules that never touch the package at all.
+   * Both interop helpers short-circuit on `__esModule`, so the trap binds as the module itself in
+   * all three import forms: the module loads, and the refusal lands on the member a recording
+   * actually wanted rather than on every module that merely mentions the package.
    */
-  it('defers an unlisted package refusal from module load to the first member read', () => {
+  it('lets a default import of an unlisted package load, and refuses the member it uses', () => {
     const modules = loaderOver({
       'uses-default.ts': `
         import Animated from 'react-native-not-substituted'
@@ -66,8 +66,9 @@ describe('the mounted module loader', () => {
       `
     })
     const { read } = modules.load<{ read: () => unknown }>('mobile/src/uses-default.ts')
+    expect(typeof read).toBe('function')
     expect(() => read()).toThrow(
-      'Unspecified native mounting dependency: react-native-not-substituted'
+      'Unspecified native mounting dependency: react-native-not-substituted.default'
     )
   })
 
@@ -79,16 +80,16 @@ describe('the mounted module loader', () => {
       `
     })
     const { read } = modules.load<{ read: () => unknown }>('mobile/src/uses-named.ts')
-    expect(() => read()).toThrow('Unspecified native mounting dependency: expo-not-substituted')
+    expect(() => read()).toThrow(
+      'Unspecified native mounting dependency: expo-not-substituted.thing'
+    )
   })
 
   /**
-   * The one shape that loses the named refusal: `__importStar` copies own keys into a fresh object,
-   * of which the trap has none, so an unlisted member reads back `undefined` and fails at the call.
-   * Pinned rather than left implicit — it is what lets a screen load a module such as
-   * `platform/haptics.ts`, which imports a device package it only touches on a press.
+   * What lets a screen mount a module such as `platform/haptics.ts`, which imports a device package
+   * it only touches on a press: loading the importer is not itself a use.
    */
-  it('lets a namespace import of an unlisted package load, with undefined members', () => {
+  it('lets a namespace import of an unlisted package load, and refuses the member it reads', () => {
     const modules = loaderOver({
       'uses-namespace.ts': `
         import * as Haptics from 'expo-not-substituted'
@@ -96,6 +97,9 @@ describe('the mounted module loader', () => {
       `
     })
     const { read } = modules.load<{ read: () => unknown }>('mobile/src/uses-namespace.ts')
-    expect(read()).toBeUndefined()
+    expect(typeof read).toBe('function')
+    expect(() => read()).toThrow(
+      'Unspecified native mounting dependency: expo-not-substituted.selectionAsync'
+    )
   })
 })

mobile/src/test-support/rpc-recording/operation-module-loader.ts

@@ -55,17 +55,17 @@ export function operationModuleLoader(
       return new Proxy(
         {},
         {
-          // `__esModule` is the module system's interop marker, not a native API. Refusing it kills
-          // a default import inside `__importDefault`, before any member is read; answering
-          // `undefined` defers the refusal to the first real member, the same rule the substitute
-          // traps follow. A namespace import is the one shape that loses it: `__importStar` copies
-          // own keys into a fresh object, of which there are none, so an unlisted member of an
-          // `import * as` reads back `undefined` and fails at the call instead of at the read.
+          // `__esModule` is the module system's interop marker, not a native API. Answering `true`
+          // makes both emitted interop helpers hand this trap straight back — `__importDefault`
+          // returns it instead of wrapping it, `__importStar` returns it instead of copying its
+          // (absent) own keys — so all three import forms load and refuse at the first member read,
+          // naming the member. Substitute partials answer `undefined` instead, because there a real
+          // member object must bind as the module's default.
           get: (_target, key) => {
             if (key === '__esModule') {
-              return undefined
+              return true
             }
-            throw new Error(`Unspecified native mounting dependency: ${name}`)
+            throw new Error(`Unspecified native mounting dependency: ${name}.${String(key)}`)
           }
         }
       )