Retry-After header, support non-standard formats

src/index.ts

@@ -386,6 +386,22 @@ export class LinkChecker extends EventEmitter {
       }
     }
   }
+  // The `retry-after` header can come in either <seconds> or
+  // A specific date to go check.
+  private parseRetryAfter(retryAfterRaw: string): number {
+    let retryAfter = Number(retryAfterRaw) * 1000 + Date.now();
+    if (!isNaN(retryAfter)) return retryAfter;
+
+    retryAfter = Date.parse(retryAfterRaw);
+    if (!isNaN(retryAfter)) return retryAfter;
+
+    // handle invalid response in formats `1m30s` or `30s`
+    const matches = retryAfterRaw.match(/^(?:(\d+)m)?(\d+)s$/);
+    if (!matches) return NaN;
+    return (
+      (Number(matches[1] || 0) * 60 + Number(matches[2])) * 1000 + Date.now()
+    );
+  }
   /**
    * Check the incoming response for a `retry-after` header.  If present,
    * and if the status was an HTTP 429, calculate the date at which this
@@ -404,15 +420,8 @@ export class LinkChecker extends EventEmitter {
       return false;
     }
 
-    // The `retry-after` header can come in either <seconds> or
-    // A specific date to go check.
-    let retryAfter = Number(retryAfterRaw) * 1000 + Date.now();
-    if (isNaN(retryAfter)) {
-      retryAfter = Date.parse(retryAfterRaw);
-      if (isNaN(retryAfter)) {
-        return false;
-      }
-    }
+    const retryAfter = this.parseRetryAfter(retryAfterRaw);
+    if (isNaN(retryAfter)) return false;
 
     // check to see if there is already a request to wait for this host
     if (opts.delayCache.has(opts.url.host)) {

test/test.retry.ts

@@ -104,6 +104,56 @@ describe('retries', () => {
     scope.done();
   });
 
+  it('should retry 429s with invalid `s` suffix', async () => {
+    const scope = nock('http://fake.local')
+      .get('/')
+      .reply(429, undefined, {
+        'retry-after': '3s',
+      })
+      .get('/')
+      .reply(200);
+
+    const {promise, resolve} = invertedPromise();
+    const checker = new LinkChecker().on('retry', resolve);
+    const clock = sinon.useFakeTimers({
+      shouldAdvanceTime: true,
+    });
+    const checkPromise = checker.check({
+      path: 'test/fixtures/basic',
+      retry: true,
+    });
+    await promise;
+    await clock.tickAsync(3000);
+    const results = await checkPromise;
+    assert.ok(results.passed);
+    scope.done();
+  });
+
+  it('should retry 429s with invalid `1m1s` format', async () => {
+    const scope = nock('http://fake.local')
+      .get('/')
+      .reply(429, undefined, {
+        'retry-after': '1m1s',
+      })
+      .get('/')
+      .reply(200);
+
+    const {promise, resolve} = invertedPromise();
+    const checker = new LinkChecker().on('retry', resolve);
+    const clock = sinon.useFakeTimers({
+      shouldAdvanceTime: true,
+    });
+    const checkPromise = checker.check({
+      path: 'test/fixtures/basic',
+      retry: true,
+    });
+    await promise;
+    await clock.tickAsync(61000);
+    const results = await checkPromise;
+    assert.ok(results.passed);
+    scope.done();
+  });
+
   it('should detect requests to wait on the same host', async () => {
     const scope = nock('http://fake.local')
       .get('/1')