Add example function.

functions/first-func.yml

@@ -0,0 +1,10 @@
+version: 1.0
+provider:
+  name: openfaas
+  gateway: http://127.0.0.1:31112
+functions:
+  first-func:
+    lang: golang-mod
+    handler: ./first-func
+    image: martinheinz/first-func:latest
+

functions/first-func/handler.go

@@ -0,0 +1,20 @@
+package function
+
+import (
+	"fmt"
+	"net/http"
+
+	"github.com/openfaas-incubator/go-function-sdk"
+)
+
+// Handle a function invocation
+func Handle(req handler.Request) (handler.Response, error) {
+	var err error
+
+	message := fmt.Sprintf("Hello world, input was: %s", string(req.Body))
+
+	return handler.Response{
+		Body:       []byte(message),
+		StatusCode: http.StatusOK,
+	}, err
+}

functions/first-func/handler_test.go

@@ -0,0 +1,17 @@
+package function
+
+import (
+	"github.com/openfaas-incubator/go-function-sdk"
+	"github.com/stretchr/testify/assert"
+	"net/http"
+	"testing"
+)
+
+func TestHandleReturnsCorrectResponse(t *testing.T) {
+	expected := handler.Response{Body: []byte("Hello world, input was: John"), StatusCode: http.StatusOK}
+	response, err := Handle(handler.Request{Body: []byte("John"), Method: "GET"})
+
+	assert.Nil(t, err)
+	assert.Equal(t, response.StatusCode, expected.StatusCode)
+	assert.Equal(t, response.Body, expected.Body)
+}