feat(content): function signatures + test cases

backend/data/questions/cells-in-a-range-on-an-excel-sheet.yaml

@@ -9,6 +9,24 @@ categories:
 patterns:
   - matrix-traversal
 
+function_signature: "def cells_in_range(s: str) -> list[str]:"
+
+test_cases:
+  visible:
+    - input: { s: "K1:L2" }
+      expected: ["K1", "K2", "L1", "L2"]
+    - input: { s: "A1:F1" }
+      expected: ["A1", "B1", "C1", "D1", "E1", "F1"]
+  hidden:
+    - input: { s: "A1:A1" }
+      expected: ["A1"]
+    - input: { s: "A1:A3" }
+      expected: ["A1", "A2", "A3"]
+    - input: { s: "B2:D4" }
+      expected: ["B2", "B3", "B4", "C2", "C3", "C4", "D2", "D3", "D4"]
+    - input: { s: "Z1:Z9" }
+      expected: ["Z1", "Z2", "Z3", "Z4", "Z5", "Z6", "Z7", "Z8", "Z9"]
+
 description: |
   A cell `(r, c)` of an Excel sheet is represented as a string `"<col><row>"` where: