🧪 Add unit tests for SettingsRepository - #190

Sharing a single TestScope instance across multiple tests via a class property is an anti-pattern in kotlinx.coroutines.test. When a test finishes, the TestScope is completed/cancelled, which will cause subsequent tests using the same scope to fail or behave unpredictably.

Instead, each test should run in its own isolated TestScope by calling runTest(testDispatcher). We can refactor createRepository to be an extension function on TestScope so it can use the current test's scope.

Additionally, calling tempFolder.newFile(...) inside the produceFile lambda of PreferenceDataStoreFactory.create can throw an IOException if the file already exists or is initialized multiple times. It is safer to resolve the file path using File(tempFolder.root, ...) instead.

    private val testDispatcher = UnconfinedTestDispatcher()

    private fun TestScope.createRepository(): SettingsRepository {
        val dataStore = PreferenceDataStoreFactory.create(
            scope = this,
            produceFile = { File(tempFolder.root, "test_settings.preferences_pb") }
        )
        return SettingsRepository(dataStore)
    }

Use runTest(testDispatcher) instead of the shared testScope.runTest to ensure each test runs in its own isolated TestScope.

Use runTest(testDispatcher) instead of the shared testScope.runTest to ensure each test runs in its own isolated TestScope.

Use runTest(testDispatcher) instead of the shared testScope.runTest to ensure each test runs in its own isolated TestScope.

Use backgroundScope for test DataStore jobs

When these tests collect repository.settings, DataStore 1.1+ starts long-lived work in the scope passed to PreferenceDataStoreFactory.create; because that scope is the same TestScope that runs each runTest and is never cancelled as background work, runTest will wait for the active DataStore job and fail or time out with UncompletedCoroutinesError. Pass the current test's backgroundScope into the factory (or cancel a separate DataStore scope in teardown) so the DataStore job is cleaned up after each test.

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