feat(content): hidden test cases

backend/data/questions/word-search.yaml

@@ -27,6 +27,12 @@ test_cases:
       expected: false
     - input: { board: [["A", "B"], ["C", "D"]], word: "ABDC" }
       expected: true
+    - input: { board: [["A"]], word: "B" }
+      expected: false
+    - input: { board: [["A", "A", "A"], ["A", "A", "A"], ["A", "A", "A"]], word: "AAAAAAAAA" }
+      expected: true
+    - input: { board: [["C", "A", "A"], ["A", "A", "A"], ["B", "C", "D"]], word: "AAB" }
+      expected: true
 
 description: |
   Given an `m × n` grid of characters `board` and a string `word`, return `true` if `word` exists in the grid.