diff --git a/js/__tests__/mxml.test.js b/js/__tests__/mxml.test.js
new file mode 100644
index 0000000000..523d27e71a
--- /dev/null
+++ b/js/__tests__/mxml.test.js
@@ -0,0 +1,151 @@
+const saveMxmlOutput = require("../mxml");
+
+describe("saveMxmlOutput", () => {
+    it("should return a valid XML string for a basic input", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        [["C"], 4, 0], 
+                    ],
+                    "1": []
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).toContain("<?xml version='1.0' encoding='UTF-8'?>");
+        expect(output).toContain("<score-partwise version=\"3.1\">");
+        expect(output).toContain("<part-list>");
+        expect(output).toContain("<score-part id=\"P1\">");
+        expect(output).toContain("<part id=\"P1\">");
+    });
+
+    it("should handle multiple voices", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        [["C"], 4, 0],
+                        [["D"], 4, 0]
+                    ],
+                    "1": [
+                        [["E"], 4, 0],
+                        [["F"], 4, 0]
+                    ]
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).toContain("<score-part id=\"P1\">");
+        expect(output).toContain("<score-part id=\"P2\">");
+        expect(output).toContain("<part id=\"P1\">");
+        expect(output).toContain("<part id=\"P2\">");
+        expect(output).toContain("<step>C</step>");
+        expect(output).toContain("<step>E</step>");
+    });
+
+    it("should ignore specified elements", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        "voice one", 
+                        [["C"], 4, 0],
+                        "voice two"
+                    ]
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).not.toContain("voice one");
+        expect(output).not.toContain("voice two");
+        expect(output).toContain("<step>C</step>");
+    });
+
+    it("should handle tempo changes", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        "tempo", 120, 4, 
+                        [["C"], 4, 0]
+                    ]
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).toContain("<sound tempo=\"120\"/>");
+        expect(output).toContain("<step>C</step>");
+    });
+
+    it("should handle meter changes", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        "meter", 3, 4,
+                        [["C"], 4, 0]
+                    ]
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).toContain("<time>");
+        expect(output).toContain("<beat-type>4</beat-type>");
+        expect(output).toContain("<step>C</step>");
+    });
+
+    it("should handle crescendo and decrescendo markings", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        "begin crescendo",
+                        [["C"], 4, 0],
+                        "end crescendo",
+                        "begin decrescendo",
+                        [["D"], 4, 0],
+                        "end decrescendo"
+                    ]
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).toContain('<wedge type="crescendo"/>');
+        expect(output).toContain('<wedge type="diminuendo"/>');
+        expect(output).toContain('<wedge type="stop"/>');
+        expect(output).toContain("<step>C</step>");
+        expect(output).toContain("<step>D</step>");
+    });
+
+    it("should handle tied notes", () => {
+        const logo = {
+            notation: {
+                notationStaging: {
+                    "0": [
+                        [["C"], 4, 0],
+                        "tie",
+                        [["C"], 4, 0]
+                    ]
+                }
+            }
+        };
+
+        const output = saveMxmlOutput(logo);
+
+        expect(output).toContain('<tie type="start"/>');
+        expect(output).toContain('<tie type="stop"/>');
+    });
+});
diff --git a/js/mxml.js b/js/mxml.js
index b1a51f80da..4f6630a299 100644
--- a/js/mxml.js
+++ b/js/mxml.js
@@ -247,3 +247,6 @@ saveMxmlOutput = (logo) => {
 
     return res;
 };
+if (typeof module !== "undefined" && module.exports) {
+    module.exports = saveMxmlOutput;
+}