libpostal: discard parse containing single "suburb" label

controller/libpostal.js

@@ -76,11 +76,18 @@ function setup(libpostalService, should_execute) {
         // push err.message or err onto req.errors
         req.errors.push( _.get(err, 'message', err) );
 
+      } else if (!Array.isArray(response) || !response.length) {
+        return next();
+
       } else if (_.some(_.countBy(response, o => o.label), count => count > 1)) {
         logger.warn(`discarding libpostal parse of '${req.clean.text}' due to duplicate field assignments`);
         return next();
 
-      } else if (_.isEmpty(response)) {
+      // libpostal classifies some airports as 'suburb'
+      // when we see a single 'suburb' label, discard it.
+      // examples: 'john f kennedy international airport', 'soho'
+      } else if (response.length === 1 && response[0].label === 'suburb') {
+        logger.warn(`discarding libpostal parse of '${req.clean.text}' due to solo 'suburb' label`);
         return next();
 
       } else {
@@ -121,7 +128,6 @@ const IS_NUMERIC_REGEXP = /^\d+$/;
 
 // apply fixes for known bugs in libpostal
 function patchBuggyResponses(response){
-  if( !Array.isArray(response) || !response.length ){ return response; }
 
   // patches which are only applied when a single label is generated
   if( response.length === 1 ){

test/unit/controller/libpostal.js

@@ -770,7 +770,7 @@ module.exports.tests.bug_fixes = (test, common) => {
   test('bug fix: recast entirely numeric input - 99', t => {
     const service = (req, callback) => {
       callback(null, [{
-        'label': 'suburb',
+        'label': 'house_number',
         'value': '99'
       }]);
     };
@@ -831,6 +831,67 @@ module.exports.tests.bug_fixes = (test, common) => {
     });
   });
 
+  test('bug fix: discard single label of type "suburb"', t => {
+    const service = (req, callback) => {
+      callback(null, [{
+        'label': 'suburb',
+        'value': 'example'
+      }]);
+    };
+    const controller = libpostal(service, () => true);
+    const req = {
+      clean: {
+        text: 'example'
+      },
+      errors: []
+    };
+    controller(req, undefined, () => {
+      t.deepEquals(req, {
+        clean: {
+          text: 'example',
+          // parse discarded
+        },
+        errors: []
+      });
+
+      t.end();
+    });
+  });
+
+  test('bug fix: do not discard "suburb" when accompanied by another label', t => {
+    const service = (req, callback) => {
+      callback(null, [{
+        'label': 'road',
+        'value': 'avenue'
+      },{
+        'label': 'suburb',
+        'value': 'example'
+      }]);
+    };
+    const controller = libpostal(service, () => true);
+    const req = {
+      clean: {
+        text: 'avenue example'
+      },
+      errors: []
+    };
+    controller(req, undefined, () => {
+      t.deepEquals(req, {
+        clean: {
+          text: 'avenue example',
+          parser: 'libpostal',
+          parsed_text: {
+            street: 'avenue',
+            neighbourhood: 'example'
+          }
+        },
+        errors: []
+      });
+
+      t.end();
+    });
+  });
+
 };
 
 module.exports.all = (tape, common) => {