diff --git a/.nycrc b/.nycrc
index d79a0ddd65..63dce4516c 100644
--- a/.nycrc
+++ b/.nycrc
@@ -1,9 +1,9 @@
 {
   "check-coverage": true,
-  "lines": 98.53,
-  "functions": 96.59,
+  "lines": 98.66,
+  "functions": 97.06,
   "branches": 95.51,
-  "statements": 98.51,
+  "statements": 98.67,
   "include": [
     "src/**/*.ts"
   ],
diff --git a/src/export/packer/image-replacer.spec.ts b/src/export/packer/image-replacer.spec.ts
new file mode 100644
index 0000000000..a5f000c2df
--- /dev/null
+++ b/src/export/packer/image-replacer.spec.ts
@@ -0,0 +1,89 @@
+import { expect } from "chai";
+
+import { File, HeadingLevel, Media, Paragraph } from "file";
+
+import { ImageReplacer } from "./image-replacer";
+
+describe("ImageReplacer", () => {
+    let file: File;
+
+    beforeEach(() => {
+        file = new File({
+            creator: "Dolan Miu",
+            revision: "1",
+            lastModifiedBy: "Dolan Miu",
+        });
+
+        file.addSection({
+            children: [
+                new Paragraph({
+                    text: "title",
+                    heading: HeadingLevel.TITLE,
+                }),
+                new Paragraph({
+                    text: "Hello world",
+                    heading: HeadingLevel.HEADING_1,
+                }),
+                new Paragraph({
+                    text: "heading 2",
+                    heading: HeadingLevel.HEADING_2,
+                }),
+                new Paragraph("test text"),
+            ],
+        });
+    });
+
+    describe("#replace()", () => {
+        it("should replace properly", () => {
+            const imageReplacer = new ImageReplacer();
+            const result = imageReplacer.replace(
+                "test {test-image.png} test",
+                [
+                    {
+                        stream: Buffer.from(""),
+                        fileName: "test-image.png",
+                        dimensions: {
+                            pixels: {
+                                x: 100,
+                                y: 100,
+                            },
+                            emus: {
+                                x: 100,
+                                y: 100,
+                            },
+                        },
+                    },
+                ],
+                0,
+            );
+
+            expect(result).to.equal("test 0 test");
+        });
+    });
+
+    describe("#getMediaData()", () => {
+        it("should get media data", () => {
+            const imageReplacer = new ImageReplacer();
+            const result = imageReplacer.getMediaData("test {test-image} test", ({
+                Array: [
+                    {
+                        stream: Buffer.from(""),
+                        fileName: "test-image",
+                        dimensions: {
+                            pixels: {
+                                x: 100,
+                                y: 100,
+                            },
+                            emus: {
+                                x: 100,
+                                y: 100,
+                            },
+                        },
+                    },
+                ],
+            } as unknown) as Media);
+
+            expect(result).to.have.length(1);
+        });
+    });
+});
diff --git a/src/export/packer/packer.spec.ts b/src/export/packer/packer.spec.ts
index 18ae459b49..e40c9cb5ea 100644
--- a/src/export/packer/packer.spec.ts
+++ b/src/export/packer/packer.spec.ts
@@ -1,6 +1,6 @@
 /* tslint:disable:typedef space-before-function-paren */
 import { assert } from "chai";
-import { stub } from "sinon";
+import { mock, stub } from "sinon";
 
 import { File, HeadingLevel, Paragraph } from "file";
 
@@ -84,4 +84,32 @@ describe("Packer", () => {
             (Packer as any).compiler.compile.restore();
         });
     });
+
+    describe("#toBlob()", () => {
+        it("should create a standard docx file", async () => {
+            // tslint:disable-next-line: no-any
+            stub((Packer as any).compiler, "compile").callsFake(() => ({
+                // tslint:disable-next-line: no-empty
+                generateAsync: () => mock({}),
+            }));
+            const str = await Packer.toBlob(file);
+
+            assert.isDefined(str);
+        });
+
+        it("should handle exception if it throws any", () => {
+            // tslint:disable-next-line:no-any
+            const compiler = stub((Packer as any).compiler, "compile");
+
+            compiler.throwsException();
+            return Packer.toBlob(file).catch((error) => {
+                assert.isDefined(error);
+            });
+        });
+
+        afterEach(() => {
+            // tslint:disable-next-line:no-any
+            (Packer as any).compiler.compile.restore();
+        });
+    });
 });