vscode-extension-samples/test-provider-sample/src/parser.ts

import * as vscode from 'vscode';

const testRe = /^([0-9]+)\s*([+*/-])\s*([0-9]+)\s*=\s*([0-9]+)/;
const headingRe = /^(#+)\s*(.+)$/;

export const parseMarkdown = (text: string, events: {
  onTest(range: vscode.Range, a: number, operator: string, b: number, expected: number): void;
  onHeading(range: vscode.Range, name: string, depth: number): void;
}) => {
  const lines = text.split('\n');

  for (let lineNo = 0; lineNo < lines.length; lineNo++) {
    const line = lines[lineNo];
    const test = testRe.exec(line);
    if (test) {
      const [, a, operator, b, expected] = test;
      const range = new vscode.Range(new vscode.Position(lineNo, 0), new vscode.Position(lineNo, test[0].length));
      events.onTest(range, Number(a), operator, Number(b), Number(expected));
      continue;
    }

    const heading = headingRe.exec(line);
    if (heading) {
      const [, pounds, name] = heading;
      const range = new vscode.Range(new vscode.Position(lineNo, 0), new vscode.Position(lineNo, line.length));
      events.onHeading(range, name, pounds.length);
    }
  }
};