Test search middle ware

ModelViewIntentSample/search/src/test/java/com/novoda/movies/mvi/search/domain/SearchMiddlewareTest.kt

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+package com.novoda.movies.mvi.search.domain
+
+import com.nhaarman.mockitokotlin2.doReturn
+import com.nhaarman.mockitokotlin2.mock
+import com.nhaarman.mockitokotlin2.stub
+import com.novoda.movies.mvi.search.data.SearchBackend
+import com.novoda.movies.mvi.search.presentation.ViewSearchResults
+import io.reactivex.Single
+import io.reactivex.observers.TestObserver
+import io.reactivex.schedulers.Schedulers
+import io.reactivex.subjects.PublishSubject
+import org.junit.Before
+import org.junit.Test
+
+class SearchMiddlewareTest {
+
+    private val backend: SearchBackend = mock()
+    private val searchMiddleware = SearchMiddleware(backend, Schedulers.trampoline())
+
+    private val actions = PublishSubject.create<SearchAction>()
+    private val state = PublishSubject.create<SearchState>()
+    private lateinit var changes: TestObserver<SearchChanges>
+
+    @Before
+    fun setUp() {
+        changes = searchMiddleware.bind(actions, state).test()
+    }
+
+    @Test
+    fun `GIVEN state with query WHEN query changed THEN query is updated`() {
+        state.onNext(SearchState.Loading(queryString = "iron man"))
+
+        actions.onNext(SearchAction.ChangeQuery(queryString = "superman"))
+
+        changes.assertValue(SearchChanges.SearchQueryUpdate("superman"))
+    }
+
+    @Test
+    fun `GIVEN state with query WHEN query cleared THEN updated query is empty`() {
+        state.onNext(SearchState.Loading(queryString = "iron man"))
+
+        actions.onNext(SearchAction.ClearQuery)
+
+        changes.assertValue(SearchChanges.SearchQueryUpdate(""))
+    }
+
+    @Test
+    fun `GIVEN backend has results WHEN execute search THEN search is in progress AND search is completed`() {
+        val searchResults = SearchResults(items = listOf())
+        state.onNext(SearchState.Content(queryString = "iron man", results = ViewSearchResults()))
+        backend.stub { on { search("iron man") } doReturn Single.just(searchResults) }
+
+        actions.onNext(SearchAction.ExecuteSearch)
+
+        changes.assertValues(
+            SearchChanges.SearchInProgress,
+            SearchChanges.SearchCompleted(results = searchResults)
+        )
+    }
+
+    @Test
+    fun `GIVEN backend errors WHEN execute search THEN search is in progress AND search failed`() {
+        val exception = IllegalStateException("backend is down")
+        state.onNext(SearchState.Content(queryString = "iron man", results = ViewSearchResults()))
+        backend.stub { on { search("iron man") } doReturn (Single.error(exception)) }
+
+        actions.onNext(SearchAction.ExecuteSearch)
+
+        changes.assertValues(
+            SearchChanges.SearchInProgress,
+            SearchChanges.SearchFailed(exception)
+        )
+    }
+}