wordy: test that various syntax errors are in fact syntax errors

exercises/wordy/canonical-data.json

@@ -1,6 +1,6 @@
 {
   "exercise": "wordy",
-  "version": "1.2.0",
+  "version": "1.3.0",
   "comments": [
     "The tests that expect an 'error' should be implemented to raise",
     "an error, or indicate a failure. Implement this in a way that",
@@ -134,6 +134,46 @@
         "question": "Who is the President of the United States?"
       },
       "expected": {"error": "unknown operation"}
+    },
+    {
+      "description": "reject incomplete problem",
+      "property": "answer",
+      "input": {
+        "question": "What is 1 plus?"
+      },
+      "expected": {"error": "syntax error"}
+    },
+    {
+      "description": "reject two operations in a row",
+      "property": "answer",
+      "input": {
+        "question": "What is 1 plus plus 2?"
+      },
+      "expected": {"error": "syntax error"}
+    },
+    {
+      "description": "reject two numbers in a row",
+      "property": "answer",
+      "input": {
+        "question": "What is 1 plus 2 1?"
+      },
+      "expected": {"error": "syntax error"}
+    },
+    {
+      "description": "reject postfix notation",
+      "property": "answer",
+      "input": {
+        "question": "What is 1 2 plus?"
+      },
+      "expected": {"error": "syntax error"}
+    },
+    {
+      "description": "reject prefix notation",
+      "property": "answer",
+      "input": {
+        "question": "What is plus 1 2?"
+      },
+      "expected": {"error": "syntax error"}
     }
   ]
 }

exercises/wordy/description.md

@@ -41,6 +41,14 @@ left-to-right, _ignoring the typical order of operations._
 
 15  (i.e. not 9)
 
+## Iteration 4 — Errors
+
+The parser should reject:
+
+* Unsupported operations ("What is 52 cubed?")
+* Non-math questions ("Who is the President of the United States")
+* Word problems with invalid syntax ("What is 1 plus plus 2?")
+
 ## Bonus — Exponentials
 
 If you'd like, handle exponentials.