Add example with non-standard formatters

formatter/features/formatter.feature

@@ -0,0 +1,16 @@
+Feature:
+	Scenario:
+		Given the numbers:
+			| Summand | Summand |
+			| 1 	  | 1       |
+		When I sum them
+		Then I get 2
+
+		Given a list of proper names:
+			| Jakob       |
+			| Ludwig      |
+			| Felix       |
+			| Mendelssohn |
+			| Bartholdy |
+		When I concatenate them together
+		Then the name is "Jakob Ludwig Felix Mendelssohn Bartholdy"

formatter/features/steps/formatter.js

@@ -0,0 +1,29 @@
+const { Given, When, Then } = require('cucumber')
+const assert = require('assert')
+
+Given('the numbers:', function (dataTable) {
+  this.numbers = dataTable.rows()[0]
+ })
+
+When('I sum them', function () {
+  this.sum = this.numbers 
+    .map(x => parseInt(x))
+    .reduce((x, acc) => acc + x, 0)
+})
+
+Then('I get {int}', function (int) {
+  assert.equal(this.sum, int)
+})
+
+Given('a list of proper names:', function (dataTable) {
+  this.names = dataTable.raw()
+    .map(x => x[0])
+})
+
+When('I concatenate them together', function () {
+  this.name = this.names.join(' ')
+})
+
+Then('the name is {string}', function (string) {
+  assert.equal(this.name, string)
+})