diff --git a/src/sort/insertion/insertionSort.spec.ts b/src/sort/insertion/insertionSort.spec.ts
new file mode 100644
index 0000000..7f65509
--- /dev/null
+++ b/src/sort/insertion/insertionSort.spec.ts
@@ -0,0 +1,39 @@
+import insertionSort from './insertionSort';
+
+const sortLowToHigh = (a: number, b: number): boolean => (a > b);
+const sortHighToLow = (a: number, b: number): boolean => (a < b);
+
+describe('Insertion sort', () => {
+  it('should return an empty array when the array for sorting is empty', () => {
+    const arrayToSort: number[] = [];
+    const expectedArray: number[] = [];
+    expect(insertionSort(arrayToSort, sortLowToHigh))
+      .toEqual(expectedArray);
+  });
+
+  it('should return an array with the element', () => {
+    const arrayToSort: number[] = [14];
+    const expectedArray: number[] = [14];
+    expect(insertionSort(arrayToSort, sortLowToHigh))
+      .toEqual(expectedArray);
+  });
+
+  it('should return an array with two elements sorted from lowest to highest', () => {
+    const arrayToSort = [65, 43];
+    const expectedArray = [43, 65];
+    expect(insertionSort(arrayToSort, sortLowToHigh))
+      .toEqual(expectedArray);
+  });
+
+  it('should return an array sorted from lowest to highest', () => {
+    const arrayToSort = [43, 65, 44, 12, 67, 1, 9, 33, 21];
+    const expectedArray = [1, 9, 12, 21, 33, 43, 44, 65, 67];
+    expect(insertionSort(arrayToSort, sortLowToHigh)).toEqual(expectedArray);
+  });
+
+  it('should return an array sorted from highest to lowest', () => {
+    const arrayToSort = [43, 65, 44, 12, 67, 1, 9, 33, 21];
+    const expectedArray = [67, 65, 44, 43, 33, 21, 12, 9, 1];
+    expect(insertionSort(arrayToSort, sortHighToLow)).toEqual(expectedArray);
+  });
+});
diff --git a/src/sort/insertion/insertionSort.ts b/src/sort/insertion/insertionSort.ts
new file mode 100644
index 0000000..6f7883b
--- /dev/null
+++ b/src/sort/insertion/insertionSort.ts
@@ -0,0 +1,17 @@
+interface CompareFunction {
+  (a: number, b: number): boolean;
+}
+
+export default function insertionSort(array: number[], comparefunction: CompareFunction): number[] {
+  const myArray = array;
+  for (let j = 0; j < myArray.length; j += 1) {
+    const key = myArray[j];
+    let i = j - 1;
+    while (i >= 0 && comparefunction(myArray[i], key)) {
+      myArray[i + 1] = myArray[i];
+      i -= 1;
+    }
+    myArray[i + 1] = key;
+  }
+  return myArray;
+}