add gif link type

Signed-off-by: Kathurima Kimathi <kathurimakimathi415@gmail.com>

engagement.go

@@ -433,6 +433,10 @@ func (l *Link) validateLinkType() error {
 		if !strings.Contains(l.URL, ".png") {
 			return fmt.Errorf("%s does not end with .pdf", l.URL)
 		}
+	case LinkTypeGif:
+		if !strings.Contains(l.URL, ".gif") {
+			return fmt.Errorf("%s does not end with .gif", l.URL)
+		}
 	case LinkTypePngImage:
 		if !strings.Contains(l.URL, ".png") {
 			return fmt.Errorf("%s does not end with .png", l.URL)
@@ -722,6 +726,7 @@ const (
 	LinkTypePngImage     LinkType = "PNG_IMAGE"
 	LinkTypePdfDocument  LinkType = "PDF_DOCUMENT"
 	LinkTypeSvgImage     LinkType = "SVG_IMAGE"
+	LinkTypeGif          LinkType = "GIF"
 	LinkTypeDefault      LinkType = "DEFAULT"
 )
 
@@ -731,13 +736,14 @@ var AllLinkType = []LinkType{
 	LinkTypePngImage,
 	LinkTypePdfDocument,
 	LinkTypeSvgImage,
+	LinkTypeGif,
 	LinkTypeDefault,
 }
 
 // IsValid is true only when a link type is avalid
 func (e LinkType) IsValid() bool {
 	switch e {
-	case LinkTypeYoutubeVideo, LinkTypePngImage, LinkTypePdfDocument, LinkTypeSvgImage, LinkTypeDefault:
+	case LinkTypeYoutubeVideo, LinkTypePngImage, LinkTypePdfDocument, LinkTypeSvgImage, LinkTypeGif, LinkTypeDefault:
 		return true
 	}
 	return false
@@ -1016,6 +1022,20 @@ func GetPDFDocumentLink(url string, title string, description string, thumbnailU
 	}
 }
 
+// GetGIFLink returns an initialized GIF link.
+//
+// It is used in testing and default data generation.
+func GetGIFLink(url string, title string, description string, thumbnailURL string) Link {
+	return Link{
+		ID:          ksuid.New().String(),
+		URL:         url,
+		LinkType:    LinkTypeGif,
+		Title:       title,
+		Description: description,
+		Thumbnail:   thumbnailURL,
+	}
+}
+
 // getSchemaURL serves JSON schema from this server and only falls back to a
 // remote schema host when the local server cannot serve the JSON schema files.
 // This has been done so as to reduce the impact of the network and DNS on the

engagement_test.go

@@ -1015,6 +1015,11 @@ func TestLinkType_MarshalGQL(t *testing.T) {
 			e:     feedlib.LinkTypeYoutubeVideo,
 			wantW: `"YOUTUBE_VIDEO"`,
 		},
+		{
+			name:  "GIF",
+			e:     feedlib.LinkTypeGif,
+			wantW: `"GIF"`,
+		},
 	}
 	for _, tt := range tests {
 		t.Run(tt.name, func(t *testing.T) {