feat: add expectLogTimes helper

README.md

@@ -133,6 +133,7 @@ try {
   console.error('Something failed');
 
   await logHelper.expectLog('Something happened');
+  logHelper.expectLogTimes('Something happened', 1);
   logHelper.expectNoLog('Unexpected error');
 } finally {
   logHelper.restore();
@@ -141,6 +142,8 @@ try {
 console.log(logHelper.logs);
 ```
 
+`expectLogTimes(pattern, times)` synchronously asserts how many times a string or regular expression matches the captured output.
+
 ### normalizeEol
 
 Normalizes CRLF line endings to LF.

src/proxyConsole.ts

@@ -38,6 +38,7 @@ const matchPattern = (
 export const createLogHelper = () => {
   const logs: string[] = [];
   const originalLogs: string[] = [];
+  let rawOutput = '';
 
   const logPatterns = new Set<{
     pattern: LogPattern;
@@ -47,12 +48,14 @@ export const createLogHelper = () => {
 
   const clearLogs = () => {
     logs.splice(0);
+    rawOutput = '';
   };
 
-  const addLog = (input: string) => {
+  const addLog = (input: string, options?: { newline?: boolean }) => {
     const log = stripAnsi(input);
     logs.push(log);
     originalLogs.push(input);
+    rawOutput += options?.newline ? `${input}\n` : input;
 
     for (const { pattern, resolve, options } of logPatterns) {
       if (matchPattern(log, pattern, options)) {
@@ -112,13 +115,46 @@ export const createLogHelper = () => {
     }
   };
 
+  /** Assert the number of non-overlapping matches in the captured output. */
+  const expectLogTimes = (pattern: string | RegExp, times: number) => {
+    const output = stripAnsi(rawOutput);
+    let actualTimes = 0;
+
+    if (typeof pattern === 'string') {
+      let position = 0;
+      while (position <= output.length) {
+        position = output.indexOf(pattern, position);
+        if (position === -1) {
+          break;
+        }
+        actualTimes++;
+        position += pattern.length || 1;
+      }
+    } else {
+      const regexp = new RegExp(
+        pattern.source,
+        pattern.flags.includes('g') ? pattern.flags : `${pattern.flags}g`,
+      );
+      actualTimes = output.match(regexp)?.length ?? 0;
+    }
+
+    if (actualTimes !== times) {
+      const title = styleText(['bold', 'red'], 'Unexpected log count.');
+      const expected = styleText('yellow', pattern.toString());
+      throw new Error(
+        `${title}\nPattern: ${expected}\nExpected: ${times}\nReceived: ${actualTimes}\nGet:\n${originalLogs.join('\n')}`,
+      );
+    }
+  };
+
   return {
     logs,
     originalLogs,
     addLog,
     clearLogs,
     expectLog,
     expectNoLog,
+    expectLogTimes,
   };
 };
 
@@ -156,7 +192,7 @@ export const proxyConsole = ({
           return typeof arg === 'object' ? JSON.stringify(arg) : String(arg);
         })
         .join(' ');
-      logHelper.addLog(logMessage);
+      logHelper.addLog(logMessage, { newline: true });
     };
   }
 

tests/proxyConsole.test.ts

@@ -1,5 +1,5 @@
 import { expect, test } from 'rstack/test';
-import { proxyConsole } from '../src/index';
+import { createLogHelper, proxyConsole } from '../src/index';
 
 test('should capture console output and expose the Rsbuild log helpers', async () => {
   const originalLog = console.log;
@@ -18,6 +18,8 @@ test('should capture console output and expose the Rsbuild log helpers', async (
       'second log',
     ]);
     expect(() => logHelper.expectNoLog('missing log')).not.toThrow();
+    logHelper.expectLogTimes('{"value":1}second log', 0);
+    logHelper.expectLogTimes(/^second log$/m, 1);
 
     logHelper.clearLogs();
     expect(logHelper.logs).toEqual([]);
@@ -45,3 +47,30 @@ test('should support strict and POSIX log matching', async () => {
     logHelper.restore();
   }
 });
+
+test('should count log occurrences across output chunks', () => {
+  const logHelper = createLogHelper();
+  const message = 'watching for changes...';
+
+  logHelper.addLog(`${message}\n${message}\nwatching for `);
+  logHelper.addLog('changes...\n');
+  logHelper.expectLogTimes(message, 3);
+  logHelper.expectLogTimes(/watching for changes\.\.\./, 3);
+
+  expect(() => logHelper.expectLogTimes(message, 1)).toThrow(
+    'Expected: 1\nReceived: 3',
+  );
+
+  logHelper.clearLogs();
+  logHelper.expectLogTimes(message, 0);
+  logHelper.addLog(message);
+  logHelper.expectLogTimes(message, 1);
+});
+
+test('should strip ANSI sequences after joining output chunks', () => {
+  const logHelper = createLogHelper();
+
+  logHelper.addLog('watching for \u001B[3');
+  logHelper.addLog('9mchanges...\n');
+  logHelper.expectLogTimes('watching for changes...', 1);
+});