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239 lines
8.4 KiB
Markdown
239 lines
8.4 KiB
Markdown
# Generating Accessibility Reports
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Build a CLI tool that analyzes web page accessibility using the Playwright MCP server and generates detailed WCAG-compliant reports with optional test generation.
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> **Runnable example:** [recipe/AccessibilityReport.java](recipe/AccessibilityReport.java)
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>
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> ```bash
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> jbang recipe/AccessibilityReport.java
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> ```
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## Example scenario
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You want to audit a website's accessibility compliance. This tool navigates to a URL using Playwright, captures an accessibility snapshot, and produces a structured report covering WCAG criteria like landmarks, heading hierarchy, focus management, and touch targets. It can also generate Playwright test files to automate future accessibility checks.
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## Prerequisites
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Install [JBang](https://www.jbang.dev/) and ensure `npx` is available (Node.js installed) for the Playwright MCP server:
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```bash
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# macOS (using Homebrew)
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brew install jbangdev/tap/jbang
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# Verify npx is available (needed for Playwright MCP)
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npx --version
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```
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## Usage
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```bash
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jbang recipe/AccessibilityReport.java
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# Enter a URL when prompted
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```
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## Full example: AccessibilityReport.java
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```java
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///usr/bin/env jbang "$0" "$@" ; exit $?
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//DEPS com.github:copilot-sdk-java:0.2.1-java.1
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import com.github.copilot.sdk.*;
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import com.github.copilot.sdk.events.*;
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import com.github.copilot.sdk.json.*;
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import java.io.*;
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import java.util.*;
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import java.util.concurrent.*;
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public class AccessibilityReport {
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public static void main(String[] args) throws Exception {
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System.out.println("=== Accessibility Report Generator ===\n");
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var reader = new BufferedReader(new InputStreamReader(System.in));
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System.out.print("Enter URL to analyze: ");
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String url = reader.readLine().trim();
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if (url.isEmpty()) {
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System.out.println("No URL provided. Exiting.");
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return;
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}
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if (!url.startsWith("http://") && !url.startsWith("https://")) {
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url = "https://" + url;
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}
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System.out.printf("%nAnalyzing: %s%n", url);
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System.out.println("Please wait...\n");
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try (var client = new CopilotClient()) {
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client.start().get();
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// Configure Playwright MCP server for browser automation
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var mcpConfig = new McpServerConfig()
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.setType("local")
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.setCommand("npx")
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.setArgs(List.of("@playwright/mcp@latest"))
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.setTools(List.of("*"));
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var session = client.createSession(
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new SessionConfig()
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.setOnPermissionRequest(PermissionHandler.APPROVE_ALL)
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.setModel("claude-opus-4.6")
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.setStreaming(true)
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.setMcpServers(Map.of("playwright", mcpConfig))
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).get();
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// Stream output token-by-token
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var idleLatch = new CountDownLatch(1);
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session.on(AssistantMessageDeltaEvent.class,
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ev -> System.out.print(ev.getData().deltaContent()));
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session.on(SessionIdleEvent.class,
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ev -> idleLatch.countDown());
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session.on(SessionErrorEvent.class, ev -> {
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System.err.printf("%nError: %s%n", ev.getData().message());
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idleLatch.countDown();
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});
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String prompt = """
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Use the Playwright MCP server to analyze the accessibility of this webpage: %s
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Please:
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1. Navigate to the URL using playwright-browser_navigate
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2. Take an accessibility snapshot using playwright-browser_snapshot
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3. Analyze the snapshot and provide a detailed accessibility report
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Format the report with emoji indicators:
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- 📊 Accessibility Report header
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- ✅ What's Working Well (table with Category, Status, Details)
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- ⚠️ Issues Found (table with Severity, Issue, WCAG Criterion, Recommendation)
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- 📋 Stats Summary (links, headings, focusable elements, landmarks)
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- ⚙️ Priority Recommendations
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Use ✅ for pass, 🔴 for high severity issues, 🟡 for medium severity, ❌ for missing items.
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Include actual findings from the page analysis.
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""".formatted(url);
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session.send(new MessageOptions().setPrompt(prompt));
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idleLatch.await();
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System.out.println("\n\n=== Report Complete ===\n");
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// Prompt user for test generation
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System.out.print("Would you like to generate Playwright accessibility tests? (y/n): ");
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String generateTests = reader.readLine().trim();
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if (generateTests.equalsIgnoreCase("y") || generateTests.equalsIgnoreCase("yes")) {
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var testLatch = new CountDownLatch(1);
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session.on(SessionIdleEvent.class,
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ev -> testLatch.countDown());
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String testPrompt = """
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Based on the accessibility report you just generated for %s,
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create Playwright accessibility tests in Java.
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Include tests for: lang attribute, title, heading hierarchy, alt text,
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landmarks, skip navigation, focus indicators, and touch targets.
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Use Playwright's accessibility testing features with helpful comments.
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Output the complete test file.
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""".formatted(url);
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System.out.println("\nGenerating accessibility tests...\n");
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session.send(new MessageOptions().setPrompt(testPrompt));
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testLatch.await();
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System.out.println("\n\n=== Tests Generated ===");
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}
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session.close();
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}
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}
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}
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```
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## How it works
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1. **Playwright MCP server**: Configures a local MCP server running `@playwright/mcp` to provide browser automation tools
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2. **Streaming output**: Uses `streaming: true` and `AssistantMessageDeltaEvent` for real-time token-by-token output
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3. **Accessibility snapshot**: Playwright's `browser_snapshot` tool captures the full accessibility tree of the page
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4. **Structured report**: The prompt engineers a consistent WCAG-aligned report format with emoji severity indicators
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5. **Test generation**: Optionally generates Playwright accessibility tests based on the analysis
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## Key concepts
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### MCP server configuration
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The recipe configures a local MCP server that runs alongside the session:
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```java
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var mcpConfig = new McpServerConfig()
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.setType("local")
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.setCommand("npx")
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.setArgs(List.of("@playwright/mcp@latest"))
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.setTools(List.of("*"));
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var session = client.createSession(
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new SessionConfig()
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.setOnPermissionRequest(PermissionHandler.APPROVE_ALL)
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.setMcpServers(Map.of("playwright", mcpConfig))
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).get();
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```
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This gives the model access to Playwright browser tools like `browser_navigate`, `browser_snapshot`, and `browser_click`.
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### Streaming with events
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Unlike `sendAndWait`, this recipe uses streaming for real-time output:
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```java
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session.on(AssistantMessageDeltaEvent.class,
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ev -> System.out.print(ev.getData().deltaContent()));
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session.on(SessionIdleEvent.class,
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ev -> idleLatch.countDown());
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```
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A `CountDownLatch` synchronizes the main thread with the async event stream — when the session becomes idle, the latch releases and the program continues.
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## Sample interaction
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```
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=== Accessibility Report Generator ===
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Enter URL to analyze: github.com
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Analyzing: https://github.com
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Please wait...
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📊 Accessibility Report: GitHub (github.com)
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✅ What's Working Well
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| Category | Status | Details |
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|----------|--------|---------|
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| Language | ✅ Pass | lang="en" properly set |
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| Page Title | ✅ Pass | "GitHub" is recognizable |
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| Heading Hierarchy | ✅ Pass | Proper H1/H2 structure |
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| Images | ✅ Pass | All images have alt text |
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⚠️ Issues Found
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| Severity | Issue | WCAG Criterion | Recommendation |
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|----------|-------|----------------|----------------|
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| 🟡 Medium | Some links lack descriptive text | 2.4.4 | Add aria-label to icon-only links |
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📋 Stats Summary
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- Total Links: 47
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- Total Headings: 8 (1× H1, proper hierarchy)
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- Focusable Elements: 52
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- Landmarks Found: banner ✅, navigation ✅, main ✅, footer ✅
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=== Report Complete ===
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Would you like to generate Playwright accessibility tests? (y/n): y
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Generating accessibility tests...
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[Generated test file output...]
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=== Tests Generated ===
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```
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