@Test
    @Order(3)
    void basicAutoSingleUploadSizeLimit(Page page) {
        // Arrange
        FileUpload fileUpload = page.fileupload;
        assertEquals("", fileUpload.getValue());

        // Act
        File file = locateClientSideFile("file3.csv");
        fileUpload.setValue(file, false);

        // Assert
        assertFalse(page.messages.getAllMessages().isEmpty());
        assertEquals("Invalid file size.",
                page.messages.getMessage(0).getSummary());
        assertNoJavascriptErrors();
        assertUploadedFiles(page.uploadedFiles);
        assertConfiguration(fileUpload);
    }
Tests basic auto single file upload.
p:fileUpload mode=simple auto=true multiple=false (skinSimple=true)
primefaces-integration-tests/src/test/java/org/primefaces/integrationtests/fileupload/FileUpload003Test.java