fix: Fix adding extra link for EnqueueLinksFunction with limit (#1674)

### Description

- fix adding extra link for `EnqueueLinksFunction` with `limit`

### Issues

- Closes: #1673 

### Testing

- Add tests for `enqueue_links` with `limit` argument

Author: Mantisus

src/crawlee/crawlers/_basic/_basic_crawler.py

@@ -1056,9 +1056,10 @@ def _enqueue_links_filter_iterator(
             ) and self._check_url_patterns(target_url, kwargs.get('include'), kwargs.get('exclude')):
                 yield request
 
-                limit = limit - 1 if limit is not None else None
-                if limit and limit <= 0:
-                    break
+                if limit is not None:
+                    limit -= 1
+                    if limit <= 0:
+                        break
 
     def _check_enqueue_strategy(
         self,

tests/unit/crawlers/_beautifulsoup/test_beautifulsoup_crawler.py

@@ -428,3 +428,28 @@ async def request_handler(context: BeautifulSoupCrawlingContext) -> None:
 
     assert handler_calls.called
     assert handler_calls.call_count == 1
+
+
+async def test_enqueue_links_with_limit(server_url: URL, http_client: HttpClient) -> None:
+    start_url = str(server_url / 'sub_index')
+    requests = [start_url]
+
+    crawler = BeautifulSoupCrawler(http_client=http_client)
+    visit = mock.Mock()
+
+    @crawler.router.default_handler
+    async def request_handler(context: BeautifulSoupCrawlingContext) -> None:
+        visit(context.request.url)
+        await context.enqueue_links(limit=1)
+
+    await crawler.run(requests)
+
+    first_visited = visit.call_args_list[0][0][0]
+    visited = {call[0][0] for call in visit.call_args_list}
+
+    assert first_visited == start_url
+    # Only one link should be enqueued from sub_index due to the limit
+    assert visited == {
+        start_url,
+        str(server_url / 'page_3'),
+    }

tests/unit/crawlers/_parsel/test_parsel_crawler.py

@@ -445,3 +445,28 @@ async def handler(context: ParselCrawlingContext) -> None:
             await context.enqueue_links(rq_id=queue_id, rq_name=queue_name, rq_alias=queue_alias)
 
     await crawler.run([str(server_url / 'start_enqueue')])
+
+
+async def test_enqueue_links_with_limit(server_url: URL, http_client: HttpClient) -> None:
+    start_url = str(server_url / 'sub_index')
+    requests = [start_url]
+
+    crawler = ParselCrawler(http_client=http_client)
+    visit = mock.Mock()
+
+    @crawler.router.default_handler
+    async def request_handler(context: ParselCrawlingContext) -> None:
+        visit(context.request.url)
+        await context.enqueue_links(limit=1)
+
+    await crawler.run(requests)
+
+    first_visited = visit.call_args_list[0][0][0]
+    visited = {call[0][0] for call in visit.call_args_list}
+
+    assert first_visited == start_url
+    # Only one link should be enqueued from sub_index due to the limit
+    assert visited == {
+        start_url,
+        str(server_url / 'page_3'),
+    }

tests/unit/crawlers/_playwright/test_playwright_crawler.py

@@ -1051,3 +1051,28 @@ async def failed_request_handler(context: BasicCrawlingContext, _error: Exceptio
     }
 
     await queue.drop()
+
+
+async def test_enqueue_links_with_limit(server_url: URL) -> None:
+    start_url = str(server_url / 'sub_index')
+    requests = [start_url]
+
+    crawler = PlaywrightCrawler()
+    visit = mock.Mock()
+
+    @crawler.router.default_handler
+    async def request_handler(context: PlaywrightCrawlingContext) -> None:
+        visit(context.request.url)
+        await context.enqueue_links(limit=1)
+
+    await crawler.run(requests)
+
+    first_visited = visit.call_args_list[0][0][0]
+    visited = {call[0][0] for call in visit.call_args_list}
+
+    assert first_visited == start_url
+    # Only one link should be enqueued from sub_index due to the limit
+    assert visited == {
+        start_url,
+        str(server_url / 'page_3'),
+    }