Added test case to ensure that only the header row is created when no data is passed and the keys option is set

Author: Altioc

test/config/testCsvFilesList.ts

@@ -25,6 +25,7 @@ const csvFileConfig = [
     {key: 'trimmedHeader', file: '../data/csv/trimmedHeader.csv'},
     {key: 'excelBOM', file: '../data/csv/excelBOM.csv'},
     {key: 'specifiedKeys', file: '../data/csv/specifiedKeys.csv'},
+    {key: 'specifiedKeysNoData', file: '../data/csv/specifiedKeysNoData.csv'},
     {key: 'extraLine', file: '../data/csv/extraLine.csv'},
     {key: 'noHeader', file: '../data/csv/noHeader.csv'},
     {key: 'sortedHeader', file: '../data/csv/sortedHeader.csv'},

test/data/csv/specifiedKeysNoData.csv

@@ -0,0 +1 @@
+arrayOfStrings,object.subField

test/json2csv.ts

@@ -293,6 +293,13 @@ export function runTests() {
                 assert.equal(csv, csvTestData.specifiedKeys);
             });
 
+            it('should only contain a header when given an empty array and the keys option is provided', () => {
+                const csv = json2csv(jsonTestData.noData, {
+                    keys: ['arrayOfStrings', 'object.subField']
+                });
+                assert.equal(csv, csvTestData.specifiedKeysNoData);
+            });
+
             it('should use the specified empty field value, if provided', () => {
                 jsonTestData.emptyFieldValues[0].number = undefined;