diff --git a/lib/formatters/formatter.ts b/lib/formatters/formatter.ts
index 5310ec19..d0ca6dca 100644
--- a/lib/formatters/formatter.ts
+++ b/lib/formatters/formatter.ts
@@ -14,7 +14,7 @@ export abstract class Formatter {
   integrateFastaHeaders(data: { [key: string]: string }[], fastaMapper: { [key: string]: string }): object[] {
     const key = Object.keys(data[0])[0];
     data.forEach((entry, i) => {
-      data[i] = Object.assign({ fastaHeader: fastaMapper[entry[key]] }, entry);
+      data[i] = Object.assign({ fasta_header: fastaMapper[entry[key]] }, entry);
     });
     return data;
   }
diff --git a/tests/formatters/csv_formatter.test.ts b/tests/formatters/csv_formatter.test.ts
index 2b9a3b85..2ea80c37 100644
--- a/tests/formatters/csv_formatter.test.ts
+++ b/tests/formatters/csv_formatter.test.ts
@@ -23,8 +23,8 @@ test('test convert', () => {
 });
 
 test('test format with fasta', () => {
-  //const fasta = [['>test', '5']];
-  //const object = [TestObject.testObject(), TestObject.testObject()];
-  //const csv = [`>test,${TestObject.asCsv()}`, TestObject.asCsv(), ""].join("\n");
-  //expect(formatter.format(object, fasta, false)).toBe(csv);
+  const fasta = { 5: ">test" };
+  const object = [TestObject.testObject(), TestObject.testObject()];
+  const csv = [`>test,${TestObject.asCsv()}`, `>test,${TestObject.asCsv()}`, ""].join("\n");
+  expect(formatter.format(object, fasta, false)).toBe(csv);
 });
diff --git a/tests/formatters/formatter.test.ts b/tests/formatters/formatter.test.ts
new file mode 100644
index 00000000..c041f31b
--- /dev/null
+++ b/tests/formatters/formatter.test.ts
@@ -0,0 +1,12 @@
+import { FormatterFactory } from "../../lib/formatters/formatter_factory";
+import { TestObject } from "./test_object";
+
+test('test integrate fasta headers', async () => {
+  const formatter = FormatterFactory.getFormatter("csv");
+  const fasta = { 5: ">test" };
+  const object = [TestObject.testObject(), TestObject.testObject()];
+  const integrated = [Object.assign({ fasta_header: ">test" }, TestObject.testObject()), Object.assign({ fasta_header: ">test" }, TestObject.testObject())];
+  // eslint-disable-next-line @typescript-eslint/ban-ts-comment
+  // @ts-ignore
+  expect(formatter.integrateFastaHeaders(object, fasta)).toEqual(integrated);
+});
diff --git a/tests/formatters/json_formatter.test.ts b/tests/formatters/json_formatter.test.ts
index c4e80648..42e14293 100644
--- a/tests/formatters/json_formatter.test.ts
+++ b/tests/formatters/json_formatter.test.ts
@@ -21,8 +21,8 @@ test('test convert', () => {
 });
 
 test('test format with fasta', () => {
-  //const fasta = [['>test', '5']];
-  //const object = [TestObject.testObject()];
-  //const json = '{"fasta_header":">test","integer":5,"string":"string","list":["a",2,false]}';
-  //expect(formatter.format(object, fasta, true)).toBe(json);
+  const fasta = { 5: ">test" };
+  const object = [TestObject.testObject()];
+  const json = '{"fasta_header":">test","integer":5,"string":"string","list":["a",2,false]}';
+  expect(formatter.format(object, fasta, true)).toBe(json);
 });
diff --git a/tests/formatters/xml_formatter.test.ts b/tests/formatters/xml_formatter.test.ts
index c327d034..6994861b 100644
--- a/tests/formatters/xml_formatter.test.ts
+++ b/tests/formatters/xml_formatter.test.ts
@@ -21,8 +21,8 @@ test('test convert', () => {
 });
 
 test('test format with fasta', () => {
-  //const fasta = [['>test', '5']];
-  //const object = [TestObject.testObject()];
-  //const json = '{"fasta_header":">test","integer":5,"string":"string","list":["a",2,false]}';
-  //expect(formatter.format(object, fasta, true)).toBe(json);
+  const fasta = { 5: ">test" };
+  const object = [TestObject.testObject()];
+  const xml = `<result><fasta_header>&gt;test</fasta_header>${TestObject.asXml()}</result>`;
+  expect(formatter.format(object, fasta, true)).toBe(xml);
 });