Add SysuiTestCase.runOnMainThreadAndWaitForIdleSync()

This CL introduces a runOnMainThreadAndWaitForIdleSync() utility to
easily post work in the main thread and wait for its completion in a
test. This should make it easier to work with code that has to run on
the main thread, like dialogs.

Bug: 346519570
Test: None, this is a test utility
Flag: EXEMPT test utility
Change-Id: I93790fb9a729d273b3806db9637d9a9af94d966f

1 files changed, 8 insertions, 0 deletions

diff --git a/packages/SystemUI/tests/utils/src/com/android/systemui/SysuiTestCaseExt.kt b/packages/SystemUI/tests/utils/src/com/android/systemui/SysuiTestCaseExt.kt
index 46259a6964cd..d3dccb021ff8 100644
--- a/packages/SystemUI/tests/utils/src/com/android/systemui/SysuiTestCaseExt.kt
+++ b/packages/SystemUI/tests/utils/src/com/android/systemui/SysuiTestCaseExt.kt
@@ -20,3 +20,11 @@ import com.android.systemui.kosmos.Kosmos
 import com.android.systemui.kosmos.testCase
 
 fun SysuiTestCase.testKosmos(): Kosmos = Kosmos().apply { testCase = this@testKosmos }
+
+/** Run [f] on the main thread and return its result once completed. */
+fun <T : Any> SysuiTestCase.runOnMainThreadAndWaitForIdleSync(f: () -> T): T {
+    lateinit var result: T
+    context.mainExecutor.execute { result = f() }
+    waitForIdleSync()
+    return result
+}