Chore: Pngx pdf viewer fixes (#12083)

src-ui/src/app/components/common/pdf-viewer/pdf-viewer.component.spec.ts

@@ -65,6 +65,13 @@ describe('PngxPdfViewerComponent', () => {
     const pageSpy = jest.fn()
     component.pageChange.subscribe(pageSpy)
 
+    // In real usage the viewer may have multiple pages; our pdfjs mock defaults
+    // to a single page, so explicitly simulate a multi-page document here.
+    const pdf = (component as any).pdf as { numPages: number }
+    pdf.numPages = 3
+    const viewer = (component as any).pdfViewer as PDFViewer
+    viewer.setDocument(pdf)
+
     component.zoomScale = PdfZoomScale.PageFit
     component.zoom = PdfZoomLevel.Two
     component.rotation = 90
@@ -81,7 +88,6 @@ describe('PngxPdfViewerComponent', () => {
       page: new SimpleChange(undefined, 2, false),
     })
 
-    const viewer = (component as any).pdfViewer as PDFViewer
     expect(viewer.pagesRotation).toBe(90)
     expect(viewer.currentPageNumber).toBe(2)
     expect(pageSpy).toHaveBeenCalledWith(2)
@@ -196,6 +202,8 @@ describe('PngxPdfViewerComponent', () => {
     const scaleSpy = jest.spyOn(component as any, 'applyViewerState')
     const resizeSpy = jest.spyOn(component as any, 'setupResizeObserver')
 
+    // Angular sets the input value before calling ngOnChanges; mirror that here.
+    component.src = 'test.pdf'
     component.ngOnChanges({
       src: new SimpleChange(undefined, 'test.pdf', true),
       zoomScale: new SimpleChange(
@@ -211,6 +219,25 @@ describe('PngxPdfViewerComponent', () => {
     expect(scaleSpy).not.toHaveBeenCalled()
   })
 
+  it('resets viewer state on src change', () => {
+    const mockViewer = {
+      setDocument: jest.fn(),
+      currentPageNumber: 7,
+      cleanup: jest.fn(),
+    }
+    ;(component as any).pdfViewer = mockViewer
+    ;(component as any).loadingTask = { destroy: jest.fn() }
+    jest.spyOn(component as any, 'loadDocument').mockImplementation(() => {})
+
+    component.src = 'test.pdf'
+    component.ngOnChanges({
+      src: new SimpleChange(undefined, 'test.pdf', true),
+    })
+
+    expect(mockViewer.setDocument).toHaveBeenCalledWith(null)
+    expect(mockViewer.currentPageNumber).toBe(1)
+  })
+
   it('applies viewer state after view init when already loaded', () => {
     const applySpy = jest.spyOn(component as any, 'applyViewerState')
     ;(component as any).hasLoaded = true