rea/src/domain/javascript/javascriptSemanticAnalysisSteps.test.ts

import { expect, it } from "vitest";

import {
  analyzeParsedJavaScriptSemantics,
  analyzeParsedJavaScriptSemanticsSteps,
} from "./javascriptSemanticAnalysis.js";
import { parseJavaScriptSource } from "./javascriptSourceParser.js";
import {
  traverseJavaScriptAst,
  traverseJavaScriptAstSteps,
} from "./javascriptSemanticTraversal.js";

const source = `
import { readFile } from "node:fs";
const shared = { token: "TOKEN" };
export function load(path) {
  return new Promise((resolve) => setTimeout(() => resolve(readFile(path)), 1));
}
export const box = { get() { return shared; } };
box.get().value = process.env.MODE ?? "default";
`;

it("yields between semantic phases and returns the synchronous result (#1462)", () => {
  const parsed = parseJavaScriptSource(source, "main.js");
  if (parsed === null) throw new Error("Expected parsed source");
  const steps = analyzeParsedJavaScriptSemanticsSteps(parsed);
  let yields = 0;
  let step = steps.next();
  while (step.done !== true) {
    yields += 1;
    step = steps.next();
  }
  // Every top-level phase and derived collector is a separate step.
  expect(yields).toBeGreaterThanOrEqual(13);
  const reparsed = parseJavaScriptSource(source, "main.js");
  if (reparsed === null) throw new Error("Expected parsed source");
  expect(step.value).toEqual(analyzeParsedJavaScriptSemantics(reparsed));
});

it("traverses a large tree in steps with the synchronous visit order (#1462)", () => {
  const parsed = parseJavaScriptSource(
    Array.from(
      { length: 400 },
      (_, index) => `const v${index} = [${index}];`,
    ).join("\n"),
    "large.js",
  );
  if (parsed === null) throw new Error("Expected parsed source");
  const visits = (record: string[]) => ({
    enter: (node: { readonly type: string }) => record.push(`+${node.type}`),
    exit: (node: { readonly type: string }) => record.push(`-${node.type}`),
  });
  const synchronous: string[] = [];
  traverseJavaScriptAst(parsed.program, visits(synchronous));
  const stepped: string[] = [];
  const steps = traverseJavaScriptAstSteps(parsed.program, visits(stepped));
  let yields = 0;
  while (steps.next().done !== true) yields += 1;
  expect(yields).toBeGreaterThan(0);
  expect(stepped).toEqual(synchronous);
});