ref: Created a dedicated method to determine if the element has overflow or not

src/lib/directives/ng2-fittext.directive.ts

@@ -109,13 +109,7 @@ export class Ng2FittextDirective
   ngAfterViewInit() {
     if (this.isVisible() && !this.isDone()) {
       if (this.fittext) {
-        const overflow = this.container
-          ? this.checkOverflow(this.container, this.el.nativeElement)
-          : this.checkOverflow(
-              this.el.nativeElement.parentElement,
-              this.el.nativeElement
-            );
-        if (overflow) {
+        if (this.hasOverflow()) {
           if (this.fontSize > this.minFontSize) {
             // iterate only until font size is bigger than minimal value
             this.setFontSize(this.calculateFontSize(this.fontSize, this.speed));
@@ -165,4 +159,13 @@ export class Ng2FittextDirective
   isVisible(): boolean {
     return this.getStartFontSizeFromHeight() > 0;
   }
+
+  hasOverflow(): boolean {
+    return this.container
+      ? this.checkOverflow(this.container, this.el.nativeElement)
+      : this.checkOverflow(
+          this.el.nativeElement.parentElement,
+          this.el.nativeElement
+        );
+  }
 }

src/lib/directives/specs/ng2-fittext.directive.spec.ts

@@ -268,4 +268,43 @@ describe('Class: Ng2FittextDirective', () => {
       ).toBe(true);
     });
   });
+
+  describe('Method: hasOverflow', () => {
+    let containerMock: any;
+    let parentElementMock: any;
+
+    beforeEach(() => {
+      containerMock = {
+        isContainer: true,
+      };
+      parentElementMock = {
+        isParentElement: true,
+      };
+      ng2FittextDirective.container = { ...containerMock };
+      ng2FittextDirective.el.nativeElement = {
+        parentElement: { ...parentElementMock },
+      } as HTMLElement;
+    });
+
+    it('Should calculate the overflow using the container if is present', () => {
+      spyOn(ng2FittextDirective, 'checkOverflow').and.callFake(
+        (parentElement: any, childrenElement: any) => {
+          expect(parentElement).toEqual(containerMock);
+          return true;
+        }
+      );
+      expect(ng2FittextDirective.hasOverflow()).toBe(true);
+    });
+
+    it('Should calculate the overflow using the parent element if the container is not present', () => {
+      delete ng2FittextDirective.container;
+      spyOn(ng2FittextDirective, 'checkOverflow').and.callFake(
+        (parentElement: any, childrenElement: any) => {
+          expect(parentElement).toEqual(parentElementMock);
+          return true;
+        }
+      );
+      expect(ng2FittextDirective.hasOverflow()).toBe(true);
+    });
+  });
 });