Use onIdle to avoid a race in FlowTests

integration/ktx/build.gradle

@@ -42,6 +42,8 @@ dependencies {
     api project(":library")
     implementation libs.androidx.core.ktx
     implementation libs.coroutines.core
+    testImplementation libs.androidx.espresso
+    testImplementation libs.androidx.espresso.idling
     testImplementation libs.androidx.test.ktx
     testImplementation libs.kotlin.junit
     testImplementation libs.androidx.test.ktx.junit

integration/ktx/src/test/java/com/bumptech/glide/integration/ktx/FlowsTest.kt

@@ -10,6 +10,7 @@ import android.graphics.drawable.ColorDrawable
 import android.graphics.drawable.Drawable
 import android.net.Uri
 import androidx.test.core.app.ApplicationProvider
+import androidx.test.espresso.Espresso.onIdle
 import androidx.test.ext.junit.runners.AndroidJUnit4
 import com.bumptech.glide.Glide
 import com.bumptech.glide.GlideBuilder
@@ -20,6 +21,7 @@ import com.bumptech.glide.load.Options
 import com.bumptech.glide.load.engine.GlideException
 import com.bumptech.glide.load.engine.cache.MemoryCache
 import com.bumptech.glide.load.engine.executor.GlideExecutor
+import com.bumptech.glide.load.engine.executor.GlideIdlingResources
 import com.bumptech.glide.load.model.ModelLoader
 import com.bumptech.glide.load.model.ModelLoaderFactory
 import com.bumptech.glide.load.model.MultiModelLoaderFactory
@@ -47,19 +49,25 @@ import kotlinx.coroutines.launch
 import kotlinx.coroutines.newSingleThreadContext
 import kotlinx.coroutines.test.runTest
 import org.junit.After
+import org.junit.Before
 import org.junit.Rule
 import org.junit.Test
 import org.junit.rules.TemporaryFolder
 import org.junit.runner.RunWith
 
 // newFile throws IOException, which triggers this warning even though there's no reasonable
 // alternative :/.
-@Suppress("BlockingMethodInNonBlockingContext")
+@Suppress("BlockingMethodInNonBlockingContext", "RedundantSuppression")
 @RunWith(AndroidJUnit4::class)
 class FlowsTest {
   private val context = ApplicationProvider.getApplicationContext<Context>()
   @get:Rule val temporaryFolder = TemporaryFolder()
 
+  @Before
+  fun setUp() {
+    GlideIdlingResources.initGlide()
+  }
+
   @After
   fun tearDown() {
     Glide.tearDown()
@@ -303,8 +311,7 @@ class FlowsTest {
   @Test
   fun flow_onClose_clearsTarget() = runTest {
     val inCache = AtomicReference<com.bumptech.glide.load.engine.Resource<*>?>()
-    Glide.init(
-      context,
+    GlideIdlingResources.initGlide(
       GlideBuilder()
         .setMemoryCache(
           object : MemoryCache {
@@ -327,11 +334,15 @@ class FlowsTest {
               inCache.set(resource)
               return null
             }
-          }
-        )
+        }
+      )
     )
     val data = Glide.with(context).load(newImageFile()).flow(100, 100).firstLoad().toList()
     assertThat(data).isNotEmpty()
+    // Glide's executor (in EngineJob's notify loop) and the coroutine race to close the resource.
+    // If Glide's executor wins, then the coroutine will be able to put the resource in the cache,
+    // but if not, the item won't be cached until after the coroutine starts back up.
+    onIdle()
     assertThat(inCache.get()).isNotNull()
   }
 

integration/ktx/src/test/java/com/bumptech/glide/load/engine/executor/GlideIdlingResourceInit.kt

@@ -0,0 +1,36 @@
+package com.bumptech.glide.load.engine.executor
+
+import androidx.test.core.app.ApplicationProvider
+import androidx.test.espresso.IdlingRegistry
+import androidx.test.espresso.idling.concurrent.IdlingThreadPoolExecutor
+import com.bumptech.glide.Glide
+import com.bumptech.glide.GlideBuilder
+import java.util.concurrent.LinkedBlockingQueue
+import java.util.concurrent.TimeUnit
+
+object GlideIdlingResources {
+
+    fun initGlide(builder: GlideBuilder? = null) {
+        val registry = IdlingRegistry.getInstance()
+        val executor =
+            IdlingThreadPoolExecutor(
+                "glide_test_thread",
+                /* corePoolSize = */ 1,
+                /* maximumPoolSize = */ 1,
+                /* keepAliveTime = */ 1,
+                TimeUnit.SECONDS,
+                LinkedBlockingQueue()
+            ) {
+                Thread(it)
+            }
+        val glideExecutor = GlideExecutor(executor)
+        Glide.init(
+            ApplicationProvider.getApplicationContext(),
+            (builder ?: GlideBuilder())
+                .setSourceExecutor(glideExecutor)
+                .setAnimationExecutor(glideExecutor)
+                .setDiskCacheExecutor(glideExecutor)
+        )
+        registry.register(executor)
+    }
+}

settings.gradle

@@ -54,14 +54,14 @@ dependencyResolutionManagement {
 
             // Versions for dependencies
             version('compose', '1.3.2')
-            version('coroutines', '1.6.4')
+            version('coroutines', '1.7.2')
             version('dagger', '2.46.1')
             version('errorprone', '2.18.0')
             version('kotlin', '1.7.0')
             version('mockito', '5.3.1')
             version('retrofit', '2.3.0')
             version('androidx-benchmark', '1.1.1')
-            version('androidx-espresso', '3.4.0')
+            version('androidx-espresso', '3.5.1')
             // At least versions 1.5 and later require java 8 desugaring, which Glide can't
             // currently use, so we're stuck on an older version.
             version('androidx-fragment', '1.3.6')