Fix replacer error on patches with empty Runs (#2875)

* Add test to demonstrate empty strings not creating runs

* Fix Run not creating Text child for empty strings

* Simplify TextRun constructor

Since `Run` already has a option for instantiating a `Text` element, we don't need to push children here.

* Add replacer test for empty runs

* Add replacer test for empty runs

* replacer: handle patches with empty runs

* Fix incorrect test name

src/file/paragraph/run/run.ts

@@ -155,7 +155,7 @@ export class Run extends XmlComponent {
 
                 this.root.push(child);
             }
-        } else if (options.text) {
+        } else if (options.text !== undefined) {
             this.root.push(new Text(options.text));
         }
     }

src/file/paragraph/run/text-run.spec.ts

@@ -16,6 +16,14 @@ describe("TextRun", () => {
                 "w:r": [{ "w:t": [{ _attr: { "xml:space": "preserve" } }, "test"] }],
             });
         });
+
+        it("should add empty text into run", () => {
+            run = new TextRun({ text: "" });
+            const f = new Formatter().format(run);
+            expect(f).to.deep.equal({
+                "w:r": [{ "w:t": [{ _attr: { "xml:space": "preserve" } }, ""] }],
+            });
+        });
     });
 
     describe("#referenceFootnote()", () => {

src/file/paragraph/run/text-run.ts

@@ -1,14 +1,7 @@
 import { IRunOptions, Run } from "./run";
-import { Text } from "./run-components/text";
 
 export class TextRun extends Run {
     public constructor(options: IRunOptions | string) {
-        if (typeof options === "string") {
-            super({});
-            this.root.push(new Text(options));
-            return this;
-        }
-
-        super(options);
+        super(typeof options === "string" ? { text: options } : options);
     }
 }