Add default headers to configuration (#44)

* Add default headers to configuration

The dynamic values could be found in the HTTP headers (e.g. Etag). This new
configuration entry will work on the same way of the current defaults, but
being applied to the header instead of the JSON body.

Resolves #43

* Move HTTP headers overrides to defaults section of the config

README.md

@@ -81,13 +81,14 @@ In some cases, attributes in a JSON response can by dynamic (e.g unique id's, da
 ```json
 {
   "defaults": {
+    "Etag": "default-etag-value",
     "updated_at": 0,
     "foo": "foobar"
   }
 }
 ```
 
-When used with `AssertHTTPResponse`, for any response with `Content-Type: application/json`, the key-value pairs in `defaults` will be used to override the JSON response, allowing for consistent snapshot testing.
+When used with `AssertHTTPResponse`, for any response with `Content-Type: application/json`, the key-value pairs in `defaults` will be used to override the JSON response, allowing for consistent snapshot testing. Any HTTP headers will also be override for key matches in `defaults`.
 
 
 ## Using custom `__snapshot__` directory

assert.go

@@ -66,10 +66,22 @@ func assertHTTP(t *testing.T, id string, body []byte, isJSON bool) {
 	}
 
 	data := string(body)
+	lines := strings.Split(strings.TrimSpace(data), "\n")
+
+	// empty line identifies the end of the HTTP header
+	for i, line := range lines {
+		if line == "" {
+			break
+		}
+
+		headerItem := strings.Split(line, ":")
+		if def, ok := config.Defaults[headerItem[0]]; ok {
+			lines[i] = fmt.Sprintf("%s: %s", headerItem[0], def)
+		}
+	}
 
 	// If the response body is JSON, indent.
 	if isJSON {
-		lines := strings.Split(strings.TrimSpace(data), "\n")
 		jsonStr := lines[len(lines)-1]
 
 		var jsonIface map[string]interface{}
@@ -90,9 +102,9 @@ func assertHTTP(t *testing.T, id string, body []byte, isJSON bool) {
 			t.Fatal(err)
 		}
 		lines[len(lines)-1] = string(out)
-		data = strings.Join(lines, "\n")
 	}
 
+	data = strings.Join(lines, "\n")
 	createOrUpdateSnapshot(t, id, data)
 }
 

example/__snapshots__/example.snapshot

@@ -2,6 +2,7 @@
 HTTP/1.1 200 OK
 Connection: close
 Content-Type: application/json
+Etag: default-etag-value
 
 {
   "foo": "foobar"
@@ -38,6 +39,7 @@ Hello World.
 HTTP/1.1 200 OK
 Connection: close
 Content-Type: application/json
+Etag: default-etag-value
 
 {
   "post": {

example/abide.json

@@ -1,5 +1,6 @@
 {
   "defaults": {
+    "Etag": "default-etag-value",
     "updated_at": 0,
     "foo": "foobar"
   }

example/main.go

@@ -3,6 +3,7 @@ package main
 import (
 	"encoding/json"
 	"net/http"
+	"strconv"
 	"time"
 
 	"github.com/beme/abide/example/models"
@@ -20,6 +21,7 @@ func firstHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Etag", strconv.FormatInt(time.Now().UnixNano(), 10))
 	w.Write(body)
 }
 
@@ -47,6 +49,7 @@ func secondHandler(w http.ResponseWriter, r *http.Request) {
 	}
 
 	w.Header().Set("Content-Type", "application/json")
+	w.Header().Set("Etag", strconv.FormatInt(time.Now().UnixNano(), 10))
 	w.Write(body)
 }