consider postalcode-only input an error condition

sanitizer/_synthesize_analysis.js

@@ -7,6 +7,11 @@ function normalizeWhitespaceToSingleSpace(val) {
   return _.replace(_.trim(val), /\s+/g, ' ');
 }
 
+function isPostalCodeOnly(parsed_text) {
+  return Object.keys(parsed_text).length === 1 &&
+          parsed_text.hasOwnProperty('postalcode');
+}
+
 function sanitize( raw, clean ){
 
   // error & warning messages
@@ -22,7 +27,10 @@ function sanitize( raw, clean ){
 
   }, {});
 
-  if (_.isEmpty(Object.keys(clean.parsed_text))) {
+  if (isPostalCodeOnly(clean.parsed_text)) {
+    messages.errors.push('postalcode-only inputs are not supported');
+  }
+  else if (_.isEmpty(Object.keys(clean.parsed_text))) {
     messages.errors.push(
       `at least one of the following fields is required: ${fields.join(', ')}`);
   }

test/unit/sanitizer/_synthesize_analysis.js

@@ -91,6 +91,28 @@ module.exports.tests.text_parser = function(test, common) {
 
   });
 
+  test('postalcode-only parsed_text should return error', function(t) {
+    const raw = {
+      postalcode: 'postalcode value'
+    };
+
+    const clean = {};
+
+    const expected_clean = {
+      parsed_text: {
+        postalcode: 'postalcode value'
+      }
+    };
+
+    const messages = sanitizer(raw, clean);
+
+    t.deepEquals(clean, expected_clean);
+    t.deepEquals(messages.errors, ['postalcode-only inputs are not supported'], 'no errors');
+    t.deepEquals(messages.warnings, [], 'no warnings');
+    t.end();
+
+  });
+
 };
 
 module.exports.all = function (tape, common) {