Added constant EMPTY_OBJECT (an empty sealed object) that is used to indicate to the xml library that an empty XML element should be generated, and use it in the JSON hardcoded into the tests.

src/file/numbering/numbering.spec.ts

@@ -7,6 +7,8 @@ import { LevelForOverride } from "./level";
 import { Num } from "./num";
 import { Numbering } from "./numbering";
 
+import { EMPTY_OBJECT } from "file/xml-components";
+
 describe("Numbering", () => {
     let numbering: Numbering;
 
@@ -216,7 +218,7 @@ describe("AbstractNumbering", () => {
                 const level = abstractNumbering.createLevel(0, "lowerRoman", "%0.").keepLines();
                 const tree = new Formatter().format(level);
                 expect(tree["w:lvl"]).to.include({
-                    "w:pPr": [{ "w:keepLines": {} }],
+                    "w:pPr": [{ "w:keepLines": EMPTY_OBJECT }],
                 });
             });
 
@@ -225,7 +227,7 @@ describe("AbstractNumbering", () => {
                 const level = abstractNumbering.createLevel(0, "lowerRoman", "%0.").keepNext();
                 const tree = new Formatter().format(level);
                 expect(tree["w:lvl"]).to.include({
-                    "w:pPr": [{ "w:keepNext": {} }],
+                    "w:pPr": [{ "w:keepNext": EMPTY_OBJECT }],
                 });
             });
         });