tools/android/webgpu/src/androidTest/java/androidx/webgpu/AsyncHelperTest.kt

/*
 * Copyright 2025 The Android Open Source Project
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *      http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */
package androidx.webgpu

import androidx.test.ext.junit.runners.AndroidJUnit4
import androidx.test.filters.SmallTest
import androidx.webgpu.helper.WebGpu
import androidx.webgpu.helper.createWebGpu
import java.util.concurrent.Executors
import kotlinx.coroutines.CoroutineDispatcher
import kotlinx.coroutines.CoroutineScope
import kotlinx.coroutines.ExecutorCoroutineDispatcher
import kotlinx.coroutines.asCoroutineDispatcher
import kotlinx.coroutines.cancel
import kotlinx.coroutines.launch
import kotlinx.coroutines.runBlocking
import org.junit.After
import org.junit.Assert.assertEquals
import org.junit.Assume.assumeFalse
import org.junit.Before
import org.junit.Test
import org.junit.runner.RunWith
import java.util.concurrent.atomic.AtomicBoolean

@RunWith(AndroidJUnit4::class)
@SmallTest
class AsyncHelperTest {

  private val dispatcher: CoroutineDispatcher = Executors.newSingleThreadExecutor { runnable ->
    Thread(runnable, "Test-WebGPU-Thread")
  }.asCoroutineDispatcher()
  private val testScope = CoroutineScope(dispatcher)
  private lateinit var device: GPUDevice
  private lateinit var webGpu: WebGpu

  private val BASIC_SHADER = """
        @vertex fn vertexMain(@builtin(vertex_index) i : u32) ->
        @builtin(position) vec4f {
            return vec4f();
        }
        @fragment fn fragmentMain() -> @location(0) vec4f {
            return vec4f();
        } """

  @Before
  fun setup(): Unit = runBlocking {
    webGpu = createWebGpu(dispatcher)
    device = webGpu.device
    testScope.launch {
      webGpu.processEventsLoop()
    }
  }

  @After
  fun teardown() {
    if (::webGpu.isInitialized) {
      webGpu.close()
    }
    testScope.cancel()
    (dispatcher as? ExecutorCoroutineDispatcher)?.close()
  }

  @Test
  fun asyncMethodTest() {
    runBlocking {
      webGpu.execute {
        /* Set up a shader module to support the async call. */
        val shaderModule = device.createShaderModule(
          GPUShaderModuleDescriptor(shaderSourceWGSL = GPUShaderSourceWGSL(""))
        )

        val exception = assertThrowsSuspend(WebGpuException::class.java) {
          /* Call an asynchronous method, converted from a callback pattern by a helper. */
          val unused = device.createRenderPipelineAndAwait(
            GPURenderPipelineDescriptor(vertex = GPUVertexState(module = shaderModule))
          )
        }

        assertEquals(
          """Create render pipeline (async) should fail when no shader entry point exists.
                       The result was: ${exception.status}""",
          CreatePipelineAsyncStatus.ValidationError,
          exception.status
        )
      }
    }
  }

  @Test
  fun asyncMethodTestValidationPasses() {
    runBlocking {
      webGpu.execute {
        /* Set up a valid shader module and descriptor */
        val shaderModule = device.createShaderModule(
          GPUShaderModuleDescriptor(shaderSourceWGSL = GPUShaderSourceWGSL(BASIC_SHADER))
        )

        /* Call an asynchronous method, converted from a callback pattern by a helper. */
        @Suppress("UNUSED_VARIABLE")
        val unused = device.createRenderPipelineAndAwait(
          GPURenderPipelineDescriptor(
            vertex = GPUVertexState(module = shaderModule), fragment = GPUFragmentState(
              module = shaderModule,
              targets = arrayOf(GPUColorTargetState(format = TextureFormat.RGBA8Unorm))
            )
          )
        )

        /* Create render pipeline (async) should pass with a simple shader.. */
      }
    }
  }

  private fun baseCancellationTest(doCancel: Boolean): Boolean {
    val hasReturned = AtomicBoolean(false)

    runBlocking {
      webGpu.execute {
        val shaderModule = device.createShaderModule(
          GPUShaderModuleDescriptor(shaderSourceWGSL = GPUShaderSourceWGSL(BASIC_SHADER))
        )

        /* Launch the function in a new coroutine, giving us a job handle we can cancel. */
        val job = launch {
          @Suppress("UNUSED_VARIABLE")
          val unused = device.createRenderPipelineAndAwait(
            GPURenderPipelineDescriptor(
              vertex = GPUVertexState(module = shaderModule),
              fragment = GPUFragmentState(
                module = shaderModule,
                targets = arrayOf(GPUColorTargetState(format = TextureFormat.RGBA8Unorm))
              )
            )
          )
          hasReturned.set(true)
        }
        assumeFalse("The job completed before we could test it", hasReturned.get())

        if (doCancel) {
          job.cancel()
        }
        job.join()
      }
    }
    return hasReturned.get()
  }

  /**
   * Test that the async-based job will complete if it's not cancelled.
   */
  @Test
  fun asyncMethodCancellationTestControl() {
    assertEquals(
      "The async job should have completed but it failed to do so.",
      true,
      baseCancellationTest(false)
    )
  }

  /**
   * Test that the async-based job will not complete if it is cancelled.
   */
  @Test
  fun asyncMethodCancellationTest() {
    assertEquals(
      "The async job should have been cancelled but it completed.",
      false,
      baseCancellationTest(true)
    )
  }
}