Allow loading an external JSON in addition to load vendor list from U…

…RL. (#4)

cmp/cmp_test.json

@@ -0,0 +1,17 @@
+{
+  "lastUpdated": "2024-05-03T00:00:00Z",
+  "cmps": {
+    "1": {
+      "id": 1,
+      "name": "CMP #1",
+      "isCommercial": true,
+      "environments": ["Web"]
+    },
+    "2": {
+      "id": 2,
+      "name": "CMP #2",
+      "isCommercial": false,
+      "environments": ["Smartphone"]
+    }
+  }
+}

cmp/loader.go

@@ -2,6 +2,7 @@ package cmp
 
 import (
 	"encoding/json"
+	"io"
 	"net/http"
 
 	"golang.org/x/exp/maps"
@@ -20,7 +21,8 @@ type Option func(loader *Loader)
 
 // Loader is the type that contains the logic to load and parse a CMP JSON list.
 type Loader struct {
-	URL string
+	URL  string
+	JSON string
 }
 
 // CMP contains the structure of the CMP info that comes inside the JSON
@@ -38,6 +40,14 @@ func WithURL(url string) Option {
 	}
 }
 
+// WithJSON allows to pass a JSON string loaded externally so our loader
+// will parse the cmp-list JSON format for you.
+func WithJSON(json string) Option {
+	return func(cmp *Loader) {
+		cmp.JSON = json
+	}
+}
+
 // NewLoader returns a CMP vendor list loader instance.
 func NewLoader(options ...Option) *Loader {
 	loader := &Loader{
@@ -50,26 +60,41 @@ func NewLoader(options ...Option) *Loader {
 }
 
 // Unmarshal parses the JSON vendor list into a struct so we can use them.
-func (loader *Loader) Unmarshal(response *http.Response) ([]CMP, error) {
+func (loader *Loader) Unmarshal(data []byte) ([]CMP, error) {
 	type Response struct {
 		CMPS map[string]CMP `json:"cmps"`
 	}
-	data := Response{}
-	if err := json.NewDecoder(response.Body).Decode(&data); err != nil {
+	response := Response{}
+	if err := json.Unmarshal(data, &response); err != nil {
 		return []CMP{}, err
 	}
-	return maps.Values(data.CMPS), nil
+	return maps.Values(response.CMPS), nil
 }
 
-// Load is used to load the vendor list into a list of CMP information.
-func (loader *Loader) Load() ([]CMP, error) {
+// LoadHTTP is used to load the vendor list from a HTTP url.
+func (loader *Loader) LoadHTTP() ([]CMP, error) {
 	response, err := http.Get(loader.URL)
 	if err == nil {
-		return loader.Unmarshal(response)
+		if data, err := io.ReadAll(response.Body); err == nil {
+			return loader.Unmarshal(data)
+		}
 	}
 	return []CMP{}, err
 }
 
+// LoadJSON is used to load the vendor list from a received JSON string.
+func (loader *Loader) LoadJSON() ([]CMP, error) {
+	return loader.Unmarshal([]byte(loader.JSON))
+}
+
+// Load decides which CMP list we are going to load.
+func (loader *Loader) Load() ([]CMP, error) {
+	if loader.JSON != "" {
+		return loader.LoadJSON()
+	}
+	return loader.LoadHTTP()
+}
+
 // LoadIDs loads the list of vendor CMP ids globally so we can reuse it
 // with subsequent calls.
 func (loader *Loader) LoadIDs() error {

cmp/loader_test.go

@@ -1,6 +1,8 @@
 package cmp_test
 
 import (
+	"os"
+
 	"github.com/hybridtheory/iab-tcf/cmp"
 	. "github.com/onsi/ginkgo/v2"
 	. "github.com/onsi/gomega"
@@ -27,13 +29,37 @@ var _ = Describe("Loader", func() {
 
 			BeforeEach(func() {
 				loader = cmp.NewLoader(cmp.WithURL(testURL))
+				err = loader.LoadIDs()
+			})
+
+			It("triggers an error because the url is not found", func() {
+				Expect(err).To(HaveOccurred())
 			})
 
 			It("is used to retrieve the JSON", func() {
-				_, err = loader.Load()
 				Expect(err).Should(MatchError(MatchRegexp("lookup unknown-url")))
 			})
 		})
+
+		Context("with json", func() {
+			const (
+				testJSONFile = "cmp_test.json"
+			)
+
+			BeforeEach(func() {
+				contents, _ := os.ReadFile(testJSONFile)
+				loader = cmp.NewLoader(cmp.WithJSON(string(contents)))
+				err = loader.LoadIDs()
+			})
+
+			It("does not trigger an error", func() {
+				Expect(err).ToNot(HaveOccurred())
+			})
+
+			It("is used to parse the JSON", func() {
+				Expect(cmp.ValidCMPs).Should(Equal([]int{1, 2}))
+			})
+		})
 	})
 
 	Describe("load", func() {