@vijaypjavvadi/pw-emit

Shared emitter library that renders Playwright TypeScript Page Objects, spec files, and project scaffolds from a generic IR.

Powers both @vijaypjavvadi/sel2pw (planned, post-v1.0) and @vijaypjavvadi/bdd2pw (from day one).

Why this exists

Both sel2pw (Selenium Java → Playwright TS) and bdd2pw (Gherkin → Playwright TS) need to emit the same shape of Page Objects, spec files, and project scaffolds. Without this package, they'd have two copies of the emitter — and divergence would be inevitable.

pw-emit is the single source of truth for what a generated Playwright TS file looks like. It does not parse Java, does not parse Gherkin — its inputs are clean IRs, and it produces TypeScript strings.

Install

npm install @vijaypjavvadi/pw-emit

Peer dep: the target project (the one being scaffolded) needs @playwright/test ≥ 1.40 — but pw-emit itself doesn't.

Quick example

import { emitPageObject, type PageObjectIR } from "@vijaypjavvadi/pw-emit";

const ir: PageObjectIR = {
  className: "LoginPage",
  fields: [
    { api: "getByLabel", args: "'Username'", fieldName: "usernameInput" },
    { api: "getByLabel", args: "'Password'", fieldName: "passwordInput" },
    { api: "getByRole", args: "'button', { name: 'Sign in' }", fieldName: "signInButton" },
  ],
  methods: [
    {
      name: "login",
      params: [{ name: "user", type: "string" }, { name: "pass", type: "string" }],
      body: "await this.usernameInput.fill(user);\nawait this.passwordInput.fill(pass);\nawait this.signInButton.click();",
    },
  ],
};

const result = emitPageObject(ir);
console.log(result.contents);

Produces:

import { Page, Locator, expect } from "@playwright/test";

export class LoginPage {
  readonly page: Page;
  readonly usernameInput: Locator;
  readonly passwordInput: Locator;
  readonly signInButton: Locator;

  constructor(page: Page) {
    this.page = page;
    this.usernameInput = page.getByLabel("Username");
    this.passwordInput = page.getByLabel("Password");
    this.signInButton = page.getByRole("button", { name: "Sign in" });
  }

  async login(user: string, pass: string): Promise<void> {
    await this.usernameInput.fill(user);
    await this.passwordInput.fill(pass);
    await this.signInButton.click();
  }
}

Public API

Emitters

emitPageObject(ir: PageObjectIR, opts?: { selfHealingShim?: boolean }): EmitResult;
emitTestSpec(ir: TestSpecIR): EmitResult;
emitProject(opts: {
  outDir: string;
  templatesDir?: string;       // override the built-in templates
  baseUrl?: string;            // injected into playwright.config.ts
  projectName?: string;        // injected into package.json
}): Promise<{ filesWritten: string[]; warnings: ReviewItem[] }>;

Locator rendering

renderLocatorExpr(choice: LocatorChoice, pageVar?: string): string;
renderFieldDeclaration(choice: LocatorChoice): string;       // "  readonly foo: Locator;"
renderFieldAssignment(choice: LocatorChoice, pageVar?: string): string;

Naming + indent

toCamelCase(s: string): string;
toKebabCase(s: string): string;
toPascalCase(s: string): string;
pageObjectFileName(className: string): string;   // "LoginPage" → "login.page.ts"
testFileName(className: string): string;          // "LoginTest" → "login.spec.ts"
dedentAndIndent(body: string, prefix: string): string;

IR types

PageObjectIR, PomMethodIR, LocatorChoice, TestSpecIR, TestCaseIR, ReviewItem, EmitResult — all exported from the root.

Design rule that makes this work

Method bodies arrive pre-rendered. pw-emit does not transform method bodies — it places them inside a class wrapper, indents them correctly, and worries about imports. Each consumer (sel2pw, bdd2pw) is responsible for producing valid TS body strings from its own input.

This is the single decision that lets sel2pw (which rewrites raw Java method bodies) and bdd2pw (which assembles bodies from Gherkin step bindings) share an emitter without one having to know about the other's input format.

SemVer commitments

• Patch: bug fixes, additive warnings, formatting tweaks.
• Minor: new exported helpers, new optional input fields (defaulted).
• Major: any change to the emitted file shape (POM/spec format), required input fields, or removed exports.

License

MIT