migrate pure-logic tests to vitest (phase 1)

vitest/expo-stub.ts

@@ -0,0 +1,33 @@
+/*
+ * Stub for the bare `expo` package. Importing the real entry runs Expo's
+ * "winter" runtime side-effect, which does bare CJS requires (./TextDecoder
+ * etc) that don't resolve under Vitest's node environment. Node already
+ * provides TextDecoder and friends, so we just need the named exports
+ * test-reachable code pulls from `expo`.
+ *
+ * Aliased in place of `expo` via resolve.alias in vitest.config.ts.
+ */
+import {vi} from 'vitest'
+
+export function requireNativeModule(moduleName: string) {
+  if (moduleName === 'ExpoPlatformInfo') {
+    return {getIsReducedMotionEnabled: () => false}
+  }
+  if (moduleName === 'BottomSheet') {
+    return {dismissAll: () => {}}
+  }
+  return {}
+}
+
+export function requireOptionalNativeModule() {
+  return null
+}
+
+export const requireNativeView = vi.fn(() => () => null)
+
+export class NativeModule {}
+export class SharedObject {}
+export class SharedRef {}
+
+export const useEvent = vi.fn()
+export const useEventListener = vi.fn()