| **Experimental:** Compose Preview Screenshot Testing is still in development. Its features and APIs are subject to change substantially during the alpha phase. Report any feedback and issues through the [issue tracker](https://issuetracker.google.com/issues/new?component=192708&template=840533).

Screenshot testing is an effective way to verify how your UI looks to users. The
Compose Preview Screenshot Testing tool combines the simplicity and features of
[composable previews](https://developer.android.com/develop/ui/compose/tooling/previews) with the
productivity gains of running host-side screenshot tests. Compose Preview
Screenshot Testing is designed to be as easy to use as composable previews.

A screenshot test is an automated test that takes a screenshot of a piece of UI
and then compares it against a previously approved reference image. If the
images don't match, the test fails and produces an HTML report to help you
compare and find the differences.

With the Compose Preview Screenshot Testing tool, you can:

- Use `@PreviewTest` to create screenshot tests for existing or new composable previews.
- Generate reference images from those composable previews.
- Generate an HTML report that identifies changes to those previews after you make code changes.
- Use `@Preview` parameters, such as `uiMode` or `fontScale`, and multi-previews to help you scale your tests.
- Modularize your tests with the new `screenshotTest` source set.

![](https://developer.android.com/static/studio/images/compose-screenshot-testing.png) **Figure 1.** Example HTML report.

## IDE integration

While you can use the Compose Preview Screenshot Testing tool by running the
underlying Gradle tasks (`updateScreenshotTest` and `validateScreenshotTest`)
manually, Android Studio Otter 3 Feature Drop Canary 4 introduces a full IDE
integration. This lets you generate reference images, run tests, and analyze
validation failures entirely within the IDE. Here are some of the key features:

- **In-editor gutter icons.** You can now run tests or update reference images directly from the source code. Green run icons appear in the gutter next to composables and classes annotated with `@PreviewTest`.
  - **Run screenshot tests.** Execute tests specifically for a single function or for an entire class.
  - **Add or update reference images.** Trigger the update flow specifically for the selected scope.

- **Interactive reference management.** Updating reference images is now safer and more granular.
  - **New reference image generation dialog.** Instead of running a bulk Gradle task, a new dialog lets you visualize and select exactly which previews to generate or update.
  - **Preview variations.** The dialog lists all preview variations (such as light or dark mode, or different devices) individually, allowing you to check or uncheck specific items before generating images.

- **Integrated test results and diff viewer.** View results without leaving the IDE.
  - **Unified run panel.** Screenshot test results appear in the standard **Run** tool window. Tests are grouped by class and function, with pass or fail status clearly marked.
  - **Visual diff tool.** When a test fails, the **Screenshot** tab lets you compare the *Reference* , *Actual* , and *Diff* images side-by-side.
  - **Detailed attributes.** An **Attributes** tab provides metadata on failed tests, including match percentage, image dimensions, and the specific preview configuration used (for example, `uiMode` or `fontScale`).

- **Flexible test scoping.** You can now execute screenshot tests with various scopes directly from the Project View. Right-click a module, directory, file, or class to run screenshot tests specifically for that selection.

## Requirements

To use Compose Preview Screenshot Testing through the full IDE integration, your
project must meet the following requirements:

- Android Studio Panda 1 Canary 4 or higher.
- Android Gradle Plugin (AGP) version 9.0 or higher.
- Compose Preview Screenshot Testing plugin version [0.0.1-alpha13](https://developer.android.com/studio/preview/compose-screenshot-testing#0-0-1-alpha13) or higher.
- Kotlin version 1.9.20 or higher. We recommend using Kotlin 2.0 or higher so you can use the Compose Compiler Gradle plugin.
- JDK version 17 or higher.
- Compose enabled for your project. We recommend enabling Compose using the [Compose Compiler Gradle plugin](https://developer.android.com/develop/ui/compose/compiler).

If you only want to use the underlying Gradle tasks without the IDE integration,
the requirements are as follows:

- Android Studio Panda 1 Canary 4 or higher.
- Android Gradle Plugin (AGP) version 8.5.0 or higher.
- Compose Preview Screenshot Testing plugin version [0.0.1-alpha13](https://developer.android.com/studio/preview/compose-screenshot-testing#0-0-1-alpha13) or higher.
- Kotlin version 1.9.20 or higher. We recommend using Kotlin 2.0 or higher so you can use the Compose Compiler Gradle plugin.
- JDK version 17 or higher.
- Compose enabled for your project. We recommend enabling Compose using the [Compose Compiler Gradle plugin](https://developer.android.com/develop/ui/compose/compiler).

| **Note:** If you can't use the Compose Compiler Gradle plugin, you can enable Compose by [declaring a dependency on the Compose Compiler directly](https://developer.android.com/jetpack/androidx/releases/compose-kotlin#kts). Make sure you use `kotlinCompilerExtensionVersion` version 1.5.4 or higher.

## Setup

Both the integrated tool and the underlying Gradle tasks rely on the Compose
Preview Screenshot Testing plugin. To set up the plugin, follow these steps:

1. Enable the experimental property in your project's `gradle.properties` file.  

   ```text
         android.experimental.enableScreenshotTest=true
       
   ```
2. In the `android {}` block of your module-level `build.gradle.kts` file, enable the experimental flag to use the `screenshotTest` source set.  

   ```
         android {
             experimentalProperties["android.experimental.enableScreenshotTest"] = true
         }
       
   ```
3. Add the `com.android.compose.screenshot` plugin, version `0.0.1-alpha13` to your project.
   1. Add the plugin to your version catalogs file:  

      ```transact-sql
                [versions]
                agp = "9.0.0-rc03"
                kotlin = "2.1.20"
                screenshot = "0.0.1-alpha13"

                [plugins]
                screenshot = { id = "com.android.compose.screenshot", version.ref = "screenshot"}
              
      ```
   2. In your module-level `build.gradle.kts` file, add the plugin in the `plugins {}` block:  

      ```kotlin
                plugins {
                    alias(libs.plugins.screenshot)
                }
              
      ```
4. Add the [`screenshot-validation-api`](https://maven.google.com/web/index.html?q=screenshot-validation-api#com.android.tools.screenshot:screenshot-validation-api) and [`ui-tooling`](https://maven.google.com/web/index.html?q=tooling#androidx.compose.ui:ui-tooling) dependencies.
   1. Add them to your version catalogs:  

      ```transact-sql
                [libraries]
                screenshot-validation-api = { group = "com.android.tools.screenshot", name = "screenshot-validation-api", version.ref = "screenshot"}
                androidx-ui-tooling = { group = "androidx.compose.ui", name = "ui-tooling"}
              
      ```
   2. Add them to your module-level `build.gradle.kts` file:  

      ```kotlin
                dependencies {
                  screenshotTestImplementation(libs.screenshot.validation.api)
                  screenshotTestImplementation(libs.androidx.ui.tooling)
                }
              
      ```

## Designate composable previews to use for screenshot tests

To designate the composable previews you want to use for screenshot tests, mark
the previews with the `@PreviewTest` annotation. The previews must be located in
the new `screenshotTest` source set, for example:

`app/src/screenshotTest/kotlin/com/example/yourapp/ExamplePreviewScreenshotTest.kt`

You can add more composables and/or previews, including multi-previews, in
this file or other files created in the same source set.  

    package com.example.yourapp

    import androidx.compose.runtime.Composable
    import androidx.compose.ui.tooling.preview.Preview
    import com.android.tools.screenshot.PreviewTest
    import com.example.yourapp.ui.theme.MyApplicationTheme

    @PreviewTest
    @Preview(showBackground = true)
    @Composable
    fun GreetingPreview() {
        MyApplicationTheme {
            Greeting("Android!")
        }
    }

## Generate reference images

After you set up a test class, you need to generate reference images for each
preview. These reference images are used to identify changes later, after you
make code changes. To generate reference images for your composable preview
screenshot tests, follow the instructions below for the IDE integration or for
the Gradle tasks.

### In the IDE

Click the gutter icon next to a `@PreviewTest` function and select **Add/Update
Reference Images** . Select the desired previews in the dialog and click **Add**.

### With the Gradle tasks

Run the following Gradle task:

- Linux and macOS: `./gradlew updateDebugScreenshotTest` (`./gradlew :{module}:update{Variant}ScreenshotTest`)
- Windows: `gradlew updateDebugScreenshotTest` (`gradlew :{module}:update{Variant}ScreenshotTest`)

After the task completes, find the reference images in
`app/src/screenshotTestDebug/reference`
(`{module}/src/screenshotTest{Variant}/reference`).
| **Note:** The reference images are named with a concatenation of the fully-qualified name of the test function and a hash of the preview parameters, for example `com.sample.screenshottests.test1_da39a3ee_c2200e98_0.png`.

## Generate a test report

Once the reference images exist, generate a test report by following the
instructions below for the IDE integration or for the Gradle tasks.

### In the IDE

Click the gutter icon next to a `@PreviewTest` function and select **Run
'...ScreenshotTests'**.

If a test fails, click the test name in the **Run** panel. Select the
**Screenshot** tab to inspect the image diff using the integrated zoom and pan
controls.

### With the Gradle tasks

Run the validate task to take a new screenshot and compare it with the
reference image:

- Linux and macOS: `./gradlew validateDebugScreenshotTest` (`./gradlew :{module}:validate{Variant}ScreenshotTest`)
- Windows: `gradlew validateDebugScreenshotTest` (`gradlew :{module}:validate{Variant}ScreenshotTest`)

The verification task creates an HTML report at
`{module}/build/reports/screenshotTest/preview/{variant}/index.html`.

## Known issues

- **Kotlin Multiplatform (KMP):** Both the IDE and the underlying plugin are engineered exclusively for Android projects. They don't support non-Android targets in KMP projects.
- **Renaming functions:** Renaming a function annotated with `@PreviewTest` breaks the association with existing reference images. In that case, you must [regenerate reference images](https://developer.android.com/studio/preview/compose-screenshot-testing#generate-reference-images) for the new function name.

You can find the complete list of current known issues in the tool's
[issue tracker component](https://issuetracker.google.com/issues?q=status:open+componentid:1581441&s=created_time:desc). Report any other feedback and issues
through the [issue tracker](https://issuetracker.google.com/issues/new?component=192708&template=840533).

## Release updates

### 0.0.1-alpha13

This release introduces:

- Compatibility with JDK 17 or higher.
- Bug fixes and improved integration with Android Studio.

### 0.0.1-alpha12

This release introduces:

- Compatibility with Android Gradle Plugin (AGP) 9.0.
- Support for running screenshot tests on JDK 24 and higher.
- Support to configure maximum heap size.
- Fixed rendering failures and improved test stability.
- Enhanced the reporting to include percentage difference and other metadata related to new and reference images.

### 0.0.1-alpha11

This release introduces:

- Compatibility with Android Gradle Plugin (AGP) 8.13.
- Added support for parsing XML drawables with decimal values regardless of the host machine's locale.
- For a host machine using JDK 24 or higher, compatible JDK (11-23) will be picked up, provided one is installed.

### 0.0.1-alpha10

This release introduces:

- From this version, you need to mark all of your preview functions with the
  `@PreviewTest` annotation. Previews without the annotation won't be executed.

- Reference image directory is changed from
  `{module}/src/{variant}/screenshotTest/reference` to
  `{module}/src/screenshotTest{Variant}/reference`. This is to make sure those
  generated reference images won't be part of the production code, and to be
  aligned with the [directory structure](https://developer.android.com/studio/test/advanced-test-setup#create-instrumented-test-for-build-variant) of other test types.

- The `{variant}PreviewScreenshotRender` task is removed. Image rendering is
  migrated into JUnit Test Engine.

- The `update{Variant}ScreenshotTest` task will compare new rendering images to
  reference images before updating. It will only update images that have
  differences greater than a specified threshold. `--updateFilter` commandline
  flag was removed.

### 0.0.1-alpha06

This release introduces:

Image Difference Threshold: This new global threshold setting will allow you to
gain finer control over screenshot comparisons. To configure, update your
module's build.gradle.kts:  

    android {
        testOptions {
            screenshotTests {
                imageDifferenceThreshold = 0.0001f // 0.01%
            }
        }
    }

This threshold will be applied to all screenshot tests defined in the module.

- Bug Fixes: Some Compose Renderer bugs and added support for empty compose
- Performance Enhancements: Image diffing algorithm was updated to be faster