Fix some issues with transform error handling

lib/JSON2CSVTransform.js

@@ -52,7 +52,8 @@ class JSON2CSVTransform extends Transform {
               transform.pushLine(JSON.parse(line));
             } catch(e) {
               if (i !== lines.length - 1) {
-                throw e;
+                e.message = 'Invalid JSON (' + line + ')'
+                transform.emit('error', e);
               }
             }
           });
@@ -79,12 +80,14 @@ class JSON2CSVTransform extends Transform {
 
     this.parser.onToken = function (token, value) {
       transform.parser._onToken(token, value);
+
+      if (this.stack.length === 0 
+        && !transform.params.fields
+        && this.mode !== Parser.C.ARRAY 
+        && this.mode !== Parser.C.OBJECT) {
+        this.onError(new Error('params should include "fields" and/or non-empty "data" array of objects'));
+      }
       if (this.stack.length === 1) {
-        if (!transform.params.fields
-          && this.mode !== Parser.C.ARRAY 
-          && this.mode !== Parser.C.OBJECT) {
-          throw new Error('params should include "fields" and/or non-empty "data" array of objects');
-        }
         if(this.depthToEmit === undefined) {
           // If Array emit its content, else emit itself
           this.depthToEmit = (this.mode === Parser.C.ARRAY) ? 1 : 0;
@@ -98,10 +101,10 @@ class JSON2CSVTransform extends Transform {
     }
 
     this.parser.onError = function (err) {
-      if(err.message.indexOf('at position') > -1) {
+      if(err.message.indexOf('Unexpected') > -1) {
         err.message = 'Invalid JSON (' + err.message + ')';
       }
-      transform.emit('error', err)
+      transform.emit('error', err);
     }
   }
 

test/fixtures/json/defaultInvalid.json

@@ -0,0 +1,6 @@
+[
+  { "carModel": "Audi",      "price": 0,  "color": "blue" },
+  { "carModel": "BMW",       "price": 15000,  "color": "red", "transmission": "manual" },
+  { "carModel": "Mercedes",  "price": 20000,  "color": "yellow",
+  { "carModel": "Porsche",   "price": 30000,  "color": "green" }
+]

test/fixtures/json/ldjsonInvalid.json

@@ -0,0 +1,4 @@
+{ "carModel": "Audi",      "price": 0,  "color": "blue" }
+{ "carModel": "BMW",       "price": 15000,  "color": "red", "transmission": "manual" }
+{ "carModel": "Mercedes",  "price": 20000,  "color": "yellow"
+{ "carModel": "Porsche",   "price": 30000,  "color": "green" }

test/index.js

@@ -2,8 +2,9 @@
 
 const Readable = require('stream').Readable
 const test = require('tape');
-const Json2csvParser = require('../lib/json2csv').Parser;
-const Json2csvTransform = require('../lib/json2csv').Transform;
+const json2csv = require('../lib/json2csv');
+const Json2csvParser = json2csv.Parser;
+const Json2csvTransform = json2csv.Transform;
 const parseLdJson = require('../lib/parse-ldjson');
 const loadFixtures = require('./helpers/load-fixtures');
 
@@ -16,6 +17,14 @@ Promise.all([
   const jsonFixturesStreams = fixtures[1];
   const csvFixtures = fixtures[2];
 
+  test('should parse json to csv and infer the fields automatically using parse method', (t) => {
+    const csv = json2csv.parse(jsonFixtures.default);
+
+    t.ok(typeof csv === 'string');
+    t.equal(csv, csvFixtures.default);
+    t.end();
+  });
+
   test('should error if input data is not an object', (t) => {
     const input = 'not an object';
     try {
@@ -642,15 +651,52 @@ Promise.all([
       .on('error', err => t.notOk(err));
   });
 
+  test('should error on invalid ld-json input data', (t) => {
+    const opts = {
+      fields: ['carModel', 'price', 'color', 'transmission'],
+      ldjson: true
+    };
+
+    const transform = new Json2csvTransform(opts);
+    const processor = jsonFixturesStreams.ldjsonInvalid().pipe(transform);
+
+    processor.on('finish', () => {
+      t.notOk(true);
+      t.end();
+    });
+    processor.on('error', (error) => {
+      t.ok(error.message.indexOf('Invalid JSON') !== -1);
+      t.end();
+    });
+  });
+
   test('should error if input data is not an object', (t) => {
     const input = new Readable();
     input._read = () => {};
-    input.push('not an object');
+    input.push('"not an object"');
     input.push(null);
 
     const transform = new Json2csvTransform();
     const processor = input.pipe(transform);
 
+    processor.on('finish', () => {
+      t.notOk(true);
+      t.end();
+    });
+    processor.on('error', (error) => {
+      t.equal(error.message, 'params should include "fields" and/or non-empty "data" array of objects');
+      t.end();
+    });
+  });
+
+  test('should error on invalid json input data', (t) => {
+    const opts = {
+      fields: ['carModel', 'price', 'color', 'transmission']
+    };
+
+    const transform = new Json2csvTransform(opts);
+    const processor = jsonFixturesStreams.defaultInvalid().pipe(transform);
+
     processor.on('finish', () => {
       t.notOk(true);
       t.end();