Do not include empty link as key

pkg/article/article.go

@@ -20,7 +20,7 @@ func SetImageLinks(filename string, images map[string]string, prefix string) (st
 
 	if replace, ok := images[parsed.frontMatter.CoverImage]; ok && replace != "" {
 		parsed.frontMatter.CoverImage = replace
-	} else {
+	} else if parsed.frontMatter.CoverImage != "" {
 		parsed.frontMatter.CoverImage = prefix + parsed.frontMatter.CoverImage
 	}
 
@@ -31,7 +31,7 @@ func SetImageLinks(filename string, images map[string]string, prefix string) (st
 			n := node.(*ast.Image)
 			if replace, ok := images[string(n.Destination)]; ok && replace != "" {
 				n.Destination = []byte(replace)
-			} else {
+			} else if len(n.Destination) > 0 {
 				n.Destination = []byte(prefix + string(n.Destination))
 			}
 		}
@@ -66,7 +66,9 @@ func GetImageLinks(filename string) (map[string]string, error) {
 	if err := ast.Walk(n, func(node ast.Node, entering bool) (ast.WalkStatus, error) {
 		if entering && node.Kind() == ast.KindImage {
 			n := node.(*ast.Image)
-			images[string(n.Destination)] = ""
+			if len(n.Destination) > 0 {
+				images[string(n.Destination)] = ""
+			}
 		}
 		return ast.WalkContinue, nil
 	}); err != nil {

pkg/article/article_test.go

@@ -61,6 +61,25 @@ cover_image: test/./cv.jpg
 ![image](./image.png)
 [Google](www.google.com)
 ![image](./image-2.png)
+`,
+			assertion: assert.NoError,
+		},
+		{
+			name: "prefix with no entries in config",
+			args: args{
+				filename: "./testdata/testdata_nocoverimage.md",
+				images:   map[string]string{},
+				prefix:   "test/",
+			},
+			want: `---
+title: A title
+published: false
+description: A description
+tags: tag-one, tag-two
+---
+![image]()
+[Google](www.google.com)
+![image](test/./image-2.png)
 `,
 			assertion: assert.NoError,
 		},
@@ -113,6 +132,14 @@ func TestGetImageLinks(t *testing.T) {
 			},
 			assertion: assert.NoError,
 		},
+		{
+			name: "normal",
+			args: args{filename: "./testdata/testdata_nocoverimage.md"},
+			want: map[string]string{
+				"./image-2.png": "",
+			},
+			assertion: assert.NoError,
+		},
 		{
 			name:      "not found",
 			args:      args{filename: "./testdata/unknown.md"},

pkg/article/testdata/testdata_nocoverimage.md

@@ -0,0 +1,10 @@
+---
+title: "A title"
+published: false
+description: "A description"
+tags: "tag-one, tag-two"
+---
+
+![image]()
+[Google](www.google.com)
+![image](./image-2.png)