Add typing for pa11y (#43060)

Co-authored-by: Adam Zerella <adamzerella@users.noreply.github.com>

types/pa11y/index.d.ts

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+// Type definitions for pa11y 5.3
+// Project: https://github.com/pa11y/pa11y
+// Definitions by:  Adam Zerella <https://github.com/adamzerella>
+// Definitions: https://github.com/DefinitelyTyped/DefinitelyTyped
+// TypeScript Version: 3.0
+
+import { Browser, Page, } from "puppeteer";
+import { Viewport } from "puppeteer/DeviceDescriptors";
+
+type AccessibilityStandard = "Section508" | "WCAG2A" | "WCAG2AA" | "WCAG2AAA";
+
+interface LaunchConfig {
+    executablePath: string;
+    ignoreHTTPSErrors: boolean;
+}
+
+interface LogConfig {
+    debug?: () => void;
+    error?: () => void;
+    info?: () => void;
+}
+
+interface ResultIssue {
+    code: string;
+    context: string;
+    message: string;
+    selector: string;
+    type: string;
+    typeCode: number;
+}
+
+interface Results {
+    documentTitle: string;
+    pageUrl: string;
+    issues: ResultIssue[];
+}
+
+interface Options {
+    actions?: string[];
+    browser?: Browser;
+    pages?: Page[];
+    chromeLaunchConfig?: LaunchConfig;
+    headers?: object;
+    hideElements?: string;
+    ignore?: string[];
+    ignoreUrl?: boolean;
+    includeNotices?: boolean;
+    includeWarnings?: boolean;
+    level?: string;
+    log?: LogConfig;
+    method?: string;
+    postData?: string;
+    reporter?: string;
+    rootElement?: string;
+    runners?: string[];
+    rules?: string[];
+    screenCapture?: string;
+    standard?: AccessibilityStandard;
+    threshold?: number;
+    timeout?: number;
+    userAgent?: string;
+    viewport?: Viewport;
+    wait?: number;
+}
+
+declare function pa11y(url: string, options?: Options): Promise<Results>;
+
+declare namespace pa11y {
+    function isValidAction(action: string): boolean;
+}
+
+export = pa11y;

types/pa11y/pa11y-tests.ts

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+import pa11y = require('pa11y');
+
+pa11y('http://example.com/');
+
+pa11y('http://example.com/', {
+    log: {
+        debug: console.log,
+        error: console.error,
+        info: console.info
+    }
+});
+
+pa11y('http://example.com/', {
+    actions: [
+        'set field #username to exampleUser',
+        'wait for url to be http://example.com/myaccount'
+    ],
+    log: {
+        debug: console.log,
+    },
+    headers: {
+        'Content-Type': 'application/x-www-form-urlencoded'
+    },
+    method: 'POST',
+    postData: 'foo=bar&bar=baz',
+    rootElement: '#main'
+});
+
+pa11y.isValidAction('open the pod bay doors');

types/pa11y/tsconfig.json

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+{
+    "compilerOptions": {
+      "module": "commonjs",
+      "lib": [
+        "es6",
+        "dom"
+      ],
+      "noImplicitAny": true,
+      "noImplicitThis": true,
+      "strictNullChecks": true,
+      "strictFunctionTypes": true,
+      "baseUrl": "../",
+      "typeRoots": [
+        "../"
+      ],
+      "types": [
+
+      ],
+      "noEmit": true,
+      "forceConsistentCasingInFileNames": true
+    },
+    "files": [
+      "index.d.ts",
+      "pa11y-tests.ts"
+    ]
+}

types/pa11y/tslint.json

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+{
+    "extends": "dtslint/dt.json"
+}