Add test for 'new' as buffer content

tests/recipe/createWithBuffer.js

@@ -68,4 +68,25 @@ describe("Modify", () => {
         done();
       });
   });
+
+  it("Create new Writer With new buffer and file output", (done) => {
+
+    const pdfDoc = new HummusRecipe(Buffer.from("new"), null, {
+      version: 1.6,
+      author: "John Doe",
+      title: "Hummus Recipe",
+      subject: "A brand new PDF",
+    });
+    const pdfBuffer = pdfDoc
+      .createPage("letter-size")
+      .endPage()
+      .endPDF((outBuffer) => {
+          assert(outBuffer instanceof Buffer);
+          fs.writeFileSync(
+              path.join(__dirname, "../output/createWithNewBuffer.pdf"),
+              outBuffer,
+          );
+        done();
+      });
+  });
 });