fix: improve recommendation input validation for unsupported values (#676)

.gitignore

@@ -121,3 +121,4 @@ app.*.symbols
 venv/
 .venv/
 
+.DS_Store

tests/test_basic.py

@@ -182,6 +182,38 @@ def test_validate_all_valid():
     errors = validate_recommendation_inputs("Python", "Beginner", "Web", "Low")
     assert errors == [], f"Unexpected errors: {errors}"
 
+def test_validate_invalid_level():
+    """Invalid level should return an error."""
+    errors = validate_recommendation_inputs(
+        "Python",
+        "Expert",
+        "Web",
+        "Low"
+    )
+    assert any("Invalid experience level" in e for e in errors)
+
+
+def test_validate_invalid_interest():
+    """Invalid interest should return an error."""
+    errors = validate_recommendation_inputs(
+        "Python",
+        "Beginner",
+        "Blockchain",
+        "Low"
+    )
+    assert any("Invalid interest" in e for e in errors)
+
+
+def test_validate_invalid_time():
+    """Invalid time should return an error."""
+    errors = validate_recommendation_inputs(
+        "Python",
+        "Beginner",
+        "Web",
+        "Very High"
+    )
+    assert any("Invalid time availability" in e for e in errors)
+
 
 def test_validate_missing_skills():
     """An empty skills field must produce an error."""
@@ -284,6 +316,20 @@ def test_recommend_api_missing_field():
     assert response.status_code in (400, 415)
     assert "error" in response.get_json()
 
+def test_recommend_api_invalid_level():
+    """API should return 400 for invalid experience level."""
+    client = get_client()
+
+    response = client.post("/api/recommend", json={
+        "skills": "Python",
+        "level": "Expert",
+        "interest": "Data",
+        "time": "Low"
+    })
+
+    assert response.status_code == 400
+    assert "error" in response.get_json()
+
 
 def test_recommend_api_empty_body():
     """The API should return 400 when the body is not valid JSON."""

utils/recommender.py

@@ -28,6 +28,31 @@
     "c++": "cpp",
     "web dev": "javascript"
 }
+VALID_LEVELS = {
+    "beginner",
+    "intermediate",
+    "advanced"
+}
+
+VALID_TIME = {
+    "low",
+    "medium",
+    "high"
+}
+
+VALID_INTERESTS = {
+    "web",
+    "data",
+    "education",
+    "automation",
+    "games",
+    "machine learning/ai",
+    "devops",
+    "mobile",
+    "artificial intelligence",
+    "cloud computing",
+    "mobile app development",
+}
 
 
 def parse_skills(skills_string):
@@ -133,7 +158,7 @@ def get_recommendations(skills_string, level, interest, time_availability):
 
 def validate_recommendation_inputs(skills, level, interest, time_availability):
     """
-    Validate all four required fields.
+    Validate all recommendation inputs.
     Returns a list of error strings. An empty list means all inputs are valid.
     """
     errors = []
@@ -143,11 +168,26 @@ def validate_recommendation_inputs(skills, level, interest, time_availability):
 
     if not level or not level.strip():
         errors.append("Please select an experience level.")
+    elif level.strip().lower() not in VALID_LEVELS:
+        errors.append(
+            "Invalid experience level. "
+            "Choose Beginner, Intermediate, or Advanced."
+        )
 
     if not interest or not interest.strip():
         errors.append("Please select an area of interest.")
+    elif interest.strip().lower() not in VALID_INTERESTS:
+        errors.append(
+            "Invalid interest. "
+            "Choose a supported interest area."
+        )
 
     if not time_availability or not time_availability.strip():
         errors.append("Please select your time availability.")
+    elif time_availability.strip().lower() not in VALID_TIME:
+        errors.append(
+            "Invalid time availability. "
+            "Choose Low, Medium, or High."
+        )
 
     return errors