我正在嘗試測試一個列可調整大小的指令，該指令偵聽鼠標事件，如鼠標啟動，鼠標移動，鼠標按下。調整大小列.指令.tsimport { Directive, OnInit, Renderer2, Input, ElementRef, HostListener } from "@angular/core";@Directive({  selector: "[resizeColumn]"})export class ResizeColumnDirective implements OnInit {  @Input() index: number;      private startX: number;      private startWidth: number;      private column: HTMLElement;      private table: HTMLElement;      private pressed: boolean;  constructor(private renderer: Renderer2, private el: ElementRef) {    this.column = this.el.nativeElement;  }  ngOnInit() {    if (this.resizable) {      const row = this.renderer.parentNode(this.column);      this.table = this.renderer.parentNode(row);      const resizer = this.renderer.createElement("span");      this.renderer.addClass(resizer, "resize-holder");      this.renderer.appendChild(this.column, resizer);      this.renderer.listen(resizer, "mousedown", this.onMouseDown);    }  }  onMouseDown = (event: MouseEvent) => {    this.pressed = true;    this.startX = event.pageX;    this.startWidth = this.column.offsetWidth;  };  @HostListener('document: mousemove')  onMouseMove(event: MouseEvent) {    const offset = 35;    if (this.pressed && event.buttons) {      this.renderer.addClass(this.table, "resizing");      // Calculate width of column      let width =        this.startWidth + (event.pageX - this.startX - offset);      const tableCells = Array.from(this.table.querySelectorAll(".custom-row")).map(        (row: any) => row.querySelectorAll(".custom-cell").item(this.index)      );    }  };我想為此指令創建單元測試，但我無法模擬鼠標事件。我正在使用觸發器EventHandler來處理事件，但在模擬鼠標按下和鼠標移動后，我無法更新最大寬度和彈性基的值。