Add CI workflow to generate and post app screenshots on PRs

.github/workflows/screenshots.yml

@@ -0,0 +1,147 @@
+name: PR Screenshots
+
+on:
+  pull_request:
+    types: [opened, synchronize]
+
+jobs:
+  screenshots:
+    runs-on: ubuntu-latest
+    permissions:
+      contents: write
+      pull-requests: write
+
+    steps:
+      - name: Skip if last commit is a screenshot update
+        id: check
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const commits = await github.rest.pulls.listCommits({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              pull_number: context.payload.pull_request.number,
+              per_page: 1,
+            });
+            const lastMsg = commits.data.at(-1)?.commit?.message ?? '';
+            core.setOutput('skip', lastMsg.includes('[screenshots]') ? 'true' : 'false');
+
+      - name: Checkout PR branch
+        if: steps.check.outputs.skip != 'true'
+        uses: actions/checkout@v4
+        with:
+          ref: ${{ github.head_ref }}
+          token: ${{ secrets.GITHUB_TOKEN }}
+
+      - name: Set up JDK 17
+        if: steps.check.outputs.skip != 'true'
+        uses: actions/setup-java@v4
+        with:
+          java-version: '17'
+          distribution: 'temurin'
+
+      - name: Cache Gradle
+        if: steps.check.outputs.skip != 'true'
+        uses: actions/cache@v4
+        with:
+          path: |
+            ~/.gradle/caches
+            ~/.gradle/wrapper
+          key: gradle-${{ runner.os }}-${{ hashFiles('**/*.gradle*', '**/gradle-wrapper.properties') }}
+          restore-keys: gradle-${{ runner.os }}-
+
+      - name: Create local.properties
+        if: steps.check.outputs.skip != 'true'
+        run: echo "sdk.dir=$ANDROID_HOME" > local.properties
+
+      - name: Generate screenshots
+        if: steps.check.outputs.skip != 'true'
+        run: ./gradlew :app:updateDebugScreenshotTest --no-daemon
+
+      - name: Commit screenshots to PR branch
+        if: steps.check.outputs.skip != 'true'
+        run: |
+          git config user.name "github-actions[bot]"
+          git config user.email "github-actions[bot]@users.noreply.github.com"
+
+          SCREENSHOT_DIR="app/src/screenshotTestDebug/reference"
+          if [ ! -d "$SCREENSHOT_DIR" ]; then
+            echo "No screenshot directory found, skipping."
+            exit 0
+          fi
+
+          git add "$SCREENSHOT_DIR"
+          if git diff --cached --quiet; then
+            echo "No screenshot changes to commit."
+          else
+            git commit -m "[screenshots] Update preview screenshots"
+            git push
+          fi
+
+      - name: Post screenshots as PR comment
+        if: steps.check.outputs.skip != 'true'
+        uses: actions/github-script@v7
+        with:
+          script: |
+            const fs = require('fs');
+            const path = require('path');
+            const screenshotDir = 'app/src/screenshotTestDebug/reference';
+
+            if (!fs.existsSync(screenshotDir)) {
+              core.info('No screenshot directory found, skipping comment.');
+              return;
+            }
+
+            const files = fs.readdirSync(screenshotDir).filter(f => f.endsWith('.png'));
+            if (files.length === 0) {
+              core.info('No screenshots found, skipping comment.');
+              return;
+            }
+
+            const branch = context.payload.pull_request.head.ref;
+            const repo = `${context.repo.owner}/${context.repo.repo}`;
+
+            let body = '## App Screenshots\n\n';
+            body += 'Auto-generated preview screenshots for this PR:\n\n';
+            body += '<table>\n';
+
+            for (let i = 0; i < files.length; i++) {
+              const file = files[i];
+              // Extract a readable name from the filename
+              const name = file
+                .replace(/^com\.example\.myapplication\./, '')
+                .replace(/_[a-f0-9]+_[a-f0-9]+_\d+\.png$/, '')
+                .replace(/([A-Z])/g, ' $1')
+                .trim();
+
+              const url = `https://raw.githubusercontent.com/${repo}/${branch}/${screenshotDir}/${file}`;
+
+              if (i % 2 === 0) body += '<tr>\n';
+              body += `<td align="center"><strong>${name}</strong><br/><img src="${url}" width="350"/></td>\n`;
+              if (i % 2 === 1 || i === files.length - 1) body += '</tr>\n';
+            }
+
+            body += '</table>\n';
+
+            // Delete previous screenshot comments to avoid clutter
+            const comments = await github.rest.issues.listComments({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.payload.pull_request.number,
+            });
+            for (const comment of comments.data) {
+              if (comment.body?.startsWith('## App Screenshots')) {
+                await github.rest.issues.deleteComment({
+                  owner: context.repo.owner,
+                  repo: context.repo.repo,
+                  comment_id: comment.id,
+                });
+              }
+            }
+
+            await github.rest.issues.createComment({
+              owner: context.repo.owner,
+              repo: context.repo.repo,
+              issue_number: context.payload.pull_request.number,
+              body: body,
+            });

app/build.gradle.kts

@@ -2,6 +2,7 @@ plugins {
     alias(libs.plugins.android.application)
     alias(libs.plugins.kotlin.compose)
     alias(libs.plugins.secrets)
+    alias(libs.plugins.screenshot)
 }
 
 android {
@@ -36,6 +37,7 @@ android {
         compose = true
         buildConfig = true
     }
+    experimentalProperties["android.experimental.enableScreenshotTest"] = true
 }
 
 dependencies {
@@ -61,4 +63,6 @@ dependencies {
     androidTestImplementation(libs.androidx.compose.ui.test.junit4)
     debugImplementation(libs.androidx.compose.ui.tooling)
     debugImplementation(libs.androidx.compose.ui.test.manifest)
+    screenshotTestImplementation(libs.screenshot.validation.api)
+    screenshotTestImplementation(libs.androidx.compose.ui.tooling)
 }