Add test for 0 byte file

Signed-off-by: Julius Härtl <jus@bitgrid.net>

cypress/e2e/viewer.spec.js

@@ -31,6 +31,7 @@ describe('Open test.md in viewer', function() {
 
 		// Upload test files
 		cy.uploadFile('test.md', 'text/markdown')
+		cy.uploadFile('empty.md', 'text/markdown')
 	})
 
 	beforeEach(function() {
@@ -66,6 +67,29 @@ describe('Open test.md in viewer', function() {
 		cy.screenshot()
 	})
 
+	it('Open an empty file', function() {
+		cy.openFile('empty.md')
+
+		cy.log('Inspect viewer')
+		const viewer = cy.get('#viewer')
+		viewer.should('be.visible')
+			.and('have.class', 'modal-mask')
+			.and('not.have.class', 'icon-loading')
+		viewer.get('.modal-title').should('contain', 'empty.md')
+		viewer.get('.modal-header button.action-item__menutoggle')
+			.should('be.visible')
+
+		cy.log('Inspect editor')
+		const editor = viewer.get('#editor .ProseMirror')
+		editor.should('contain', '')
+
+		cy.log('Inspect menubar')
+		cy.getActionEntry('undo').should('be.visible')
+		cy.getActionEntry('bold').should('be.visible')
+
+		cy.screenshot()
+	})
+
 	it('Closes the editor', function() {
 		cy.openFile('test.md')
 		cy.get('#viewer .modal-header button.header-close').click()