feat(cses): update cses with concept of a category

tests/scrapers/test_cses.py

@@ -1,5 +1,12 @@
 from unittest.mock import Mock
-from scrapers.cses import scrape, scrape_all_problems
+
+from scrapers.cses import (
+    denormalize_category_name,
+    normalize_category_name,
+    scrape,
+    scrape_all_problems,
+    scrape_category_problems,
+)
 from scrapers.models import ProblemSummary
 
 
@@ -19,12 +26,19 @@ def test_scrape_success(mocker, mock_cses_html):
 def test_scrape_all_problems(mocker):
     mock_response = Mock()
     mock_response.text = """
-    <h1>Introductory Problems</h1>
-    <a href="/problemset/task/1068">Weird Algorithm</a>
-    <a href="/problemset/task/1083">Missing Number</a>
-    <h1>Sorting and Searching</h1>
-    <a href="/problemset/task/1084">Apartments</a>
+    <div class="content">
+        <h1>Introductory Problems</h1>
+        <ul>
+            <li><a href="/problemset/task/1068">Weird Algorithm</a></li>
+            <li><a href="/problemset/task/1083">Missing Number</a></li>
+        </ul>
+        <h1>Sorting and Searching</h1>
+        <ul>
+            <li><a href="/problemset/task/1084">Apartments</a></li>
+        </ul>
+    </div>
     """
+    mock_response.raise_for_status = Mock()
 
     mocker.patch("scrapers.cses.requests.get", return_value=mock_response)
 
@@ -45,3 +59,74 @@ def test_scrape_network_error(mocker):
     result = scrape("https://cses.fi/problemset/task/1068")
 
     assert result == []
+
+
+def test_normalize_category_name():
+    assert normalize_category_name("Sorting and Searching") == "sorting_and_searching"
+    assert normalize_category_name("Dynamic Programming") == "dynamic_programming"
+    assert normalize_category_name("Graph Algorithms") == "graph_algorithms"
+
+
+def test_denormalize_category_name():
+    assert denormalize_category_name("sorting_and_searching") == "Sorting and Searching"
+    assert denormalize_category_name("dynamic_programming") == "Dynamic Programming"
+    assert denormalize_category_name("graph_algorithms") == "Graph Algorithms"
+
+
+def test_scrape_category_problems_success(mocker):
+    mock_response = Mock()
+    mock_response.text = """
+    <div class="content">
+        <h1>General</h1>
+        <ul>
+            <li><a href="/problemset/task/1000">Test Problem</a></li>
+        </ul>
+        <h1>Sorting and Searching</h1>
+        <ul>
+            <li><a href="/problemset/task/1640">Sum of Two Values</a></li>
+            <li><a href="/problemset/task/1643">Maximum Subarray Sum</a></li>
+        </ul>
+        <h1>Dynamic Programming</h1>
+        <ul>
+            <li><a href="/problemset/task/1633">Dice Combinations</a></li>
+        </ul>
+    </div>
+    """
+    mock_response.raise_for_status = Mock()
+
+    mocker.patch("scrapers.cses.requests.get", return_value=mock_response)
+
+    result = scrape_category_problems("sorting_and_searching")
+
+    assert len(result) == 2
+    assert result[0].id == "1640"
+    assert result[0].name == "Sum of Two Values"
+    assert result[1].id == "1643"
+    assert result[1].name == "Maximum Subarray Sum"
+
+
+def test_scrape_category_problems_not_found(mocker):
+    mock_response = Mock()
+    mock_response.text = """
+    <div class="content">
+        <h1>Some Other Category</h1>
+        <ul>
+            <li><a href="/problemset/task/1000">Test Problem</a></li>
+        </ul>
+    </div>
+    """
+    mock_response.raise_for_status = Mock()
+
+    mocker.patch("scrapers.cses.requests.get", return_value=mock_response)
+
+    result = scrape_category_problems("nonexistent_category")
+
+    assert result == []
+
+
+def test_scrape_category_problems_network_error(mocker):
+    mocker.patch("scrapers.cses.requests.get", side_effect=Exception("Network error"))
+
+    result = scrape_category_problems("sorting_and_searching")
+
+    assert result == []