From 61e9b91637b1fa8c57568f5fe33e13c6f23e6960 Mon Sep 17 00:00:00 2001
From: James Hillyerd <james@hillyerd.com>
Date: Sun, 8 Jan 2017 04:09:27 +0000
Subject: [PATCH] Generic REST client (HTTP GET only) for #43

---
 rest/client/rest.go      | 56 +++++++++++++++++++++++++++++
 rest/client/rest_test.go | 77 ++++++++++++++++++++++++++++++++++++++++
 2 files changed, 133 insertions(+)
 create mode 100644 rest/client/rest.go
 create mode 100644 rest/client/rest_test.go

diff --git a/rest/client/rest.go b/rest/client/rest.go
new file mode 100644
index 0000000..323e260
--- /dev/null
+++ b/rest/client/rest.go
@@ -0,0 +1,56 @@
+package client
+
+import (
+	"encoding/json"
+	"fmt"
+	"net/http"
+	"net/url"
+)
+
+// httpClient allows http.Client to be mocked for tests
+type httpClient interface {
+	Do(*http.Request) (*http.Response, error)
+}
+
+// Generic REST restClient
+type restClient struct {
+	client  httpClient
+	baseURL *url.URL
+}
+
+// do performs an HTTP request with this client and returns the response
+func (c *restClient) do(method, uri string) (*http.Response, error) {
+	rel, err := url.Parse(uri)
+	if err != nil {
+		return nil, err
+	}
+
+	url := c.baseURL.ResolveReference(rel)
+
+	// Build the request
+	req, err := http.NewRequest(method, url.String(), nil)
+	if err != nil {
+		return nil, err
+	}
+
+	// Send the request
+	return c.client.Do(req)
+}
+
+// doGet performs a GET request with this client and marshalls the JSON response into v
+func (c *restClient) doGet(uri string, v interface{}) error {
+	resp, err := c.do("GET", uri)
+	if err != nil {
+		return err
+	}
+
+	defer func() {
+		_ = resp.Body.Close()
+	}()
+	if resp.StatusCode == http.StatusOK {
+		// Decode response body
+		return json.NewDecoder(resp.Body).Decode(v)
+	}
+
+	return fmt.Errorf("Unexpected HTTP response status %v: %s", resp.StatusCode, resp.Status)
+}
diff --git a/rest/client/rest_test.go b/rest/client/rest_test.go
new file mode 100644
index 0000000..29c0eeb
--- /dev/null
+++ b/rest/client/rest_test.go
@@ -0,0 +1,77 @@
+package client
+
+import (
+	"bytes"
+	"io/ioutil"
+	"net/http"
+	"net/url"
+	"testing"
+)
+
+const baseURLStr = "http://test.local:8080"
+
+var baseURL *url.URL
+
+func init() {
+	var err error
+	baseURL, err = url.Parse(baseURLStr)
+	if err != nil {
+		panic(err)
+	}
+}
+
+type mockHTTPClient struct {
+	req *http.Request
+}
+
+func (m *mockHTTPClient) Do(req *http.Request) (resp *http.Response, err error) {
+	m.req = req
+	resp = &http.Response{
+		Body: ioutil.NopCloser(&bytes.Buffer{}),
+	}
+
+	return
+}
+
+func TestDo(t *testing.T) {
+	var want, got string
+
+	mth := &mockHTTPClient{}
+	c := &restClient{mth, baseURL}
+
+	c.do("POST", "/dopost")
+
+	want = "POST"
+	got = mth.req.Method
+	if got != want {
+		t.Errorf("req.Method == %q, want %q", got, want)
+	}
+
+	want = baseURLStr + "/dopost"
+	got = mth.req.URL.String()
+	if got != want {
+		t.Errorf("req.URL == %q, want %q", got, want)
+	}
+}
+
+func TestDoGet(t *testing.T) {
+	var want, got string
+
+	mth := &mockHTTPClient{}
+	c := &restClient{mth, baseURL}
+
+	v := new(map[string]interface{})
+	c.doGet("/doget", &v)
+
+	want = "GET"
+	got = mth.req.Method
+	if got != want {
+		t.Errorf("req.Method == %q, want %q", got, want)
+	}
+
+	want = baseURLStr + "/doget"
+	got = mth.req.URL.String()
+	if got != want {
+		t.Errorf("req.URL == %q, want %q", got, want)
+	}
+}