OverrideWidget annotation does not work due to InstantiationException with error "SomeClass is abstract so it can't be instantiated"

[truebit]

Description

Use a abstract widget class and two subclass to implement android and iOS widgets in Page Objects. But it would fail to init the PageObjects with exception: java.lang.IllegalArgumentException: java.lang.InstantiationException: com.foobar.uitest.widgets.TheAbastractCellWidget is abstract so it can't be instantiated

Environment

• java client build version or git revision if you use some shapshot: 1.8.0_77
• Appium server version or git revision if you use some shapshot: 1.5.2
• Desktop OS/version used to run Appium if necessary: n/a
• Node.js version (unless using Appium.app|exe) or Appium CLI or Appium.app|exe: 6.0
• Mobile platform/version under test: Android
• Real device or emulator/simulator: real

Details

    @iOSFindBy(uiAutomator = ".tableViews()[0].cells()\")")
    @AndroidFindBy(id ="com.foobar:id/main_content")
    @OverrideWidget(androidUIAutomator = AndroidCellWidget.class,iOSUIAutomation = IOSCellWidget.class)
    @WithTimeout(time = 30,unit = TimeUnit.SECONDS)
    public List<TheAbastractCellWidget> cells;

Scenario: TheAbastractCellWidget is the abstract Widget class, AndroidCellWidget is the Android implementation of it and IOSCellWidget is the iOS implementation.
This code is put in a page object class FooPage

I debugged the code, it seems that buildDefaultBy() method in class WidgetByBuilder started WhatIsNeeded.DEFAULT_OR_HTML type widget initialization before OverrideWidget mechanism and then it threw exeception.

Code To Reproduce Issue [ Good To Have ]

n/a

Ecxeption stacktraces

java.lang.IllegalArgumentException: java.lang.InstantiationException: com.foobar.uitest.widgets.MyChangbaPageFeedWorkCell is abstract so it can't be instantiated

at io.appium.java_client.pagefactory.OverrideWidgetReader.getConvenientClass(OverrideWidgetReader.java:64)
at io.appium.java_client.pagefactory.OverrideWidgetReader.getDefaultOrHTMLWidgetClass(OverrideWidgetReader.java:75)
at io.appium.java_client.pagefactory.WidgetByBuilder.getByFromDeclaredClass(WidgetByBuilder.java:67)
at io.appium.java_client.pagefactory.WidgetByBuilder.buildDefaultBy(WidgetByBuilder.java:98)
at io.appium.java_client.pagefactory.DefaultElementByBuilder.buildBy(DefaultElementByBuilder.java:185)
at io.appium.java_client.pagefactory.AppiumElementLocatorFactory.createLocator(AppiumElementLocatorFactory.java:57)
at io.appium.java_client.pagefactory.AppiumElementLocatorFactory.createLocator(AppiumElementLocatorFactory.java:44)
at io.appium.java_client.pagefactory.AppiumFieldDecorator.decorateWidget(AppiumFieldDecorator.java:193)
at io.appium.java_client.pagefactory.AppiumFieldDecorator.decorate(AppiumFieldDecorator.java:160)
at org.openqa.selenium.support.PageFactory.proxyFields(PageFactory.java:113)
at org.openqa.selenium.support.PageFactory.initElements(PageFactory.java:105)
at com.foobar.uitest.pages.FooPage.(BasePage.java:32)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at org.testng.internal.MethodInvocationHelper.invokeMethod(MethodInvocationHelper.java:86)
at org.testng.internal.Invoker.invokeConfigurationMethod(Invoker.java:514)
at org.testng.internal.Invoker.invokeConfigurations(Invoker.java:215)
at org.testng.internal.Invoker.invokeMethod(Invoker.java:589)
at org.testng.internal.Invoker.invokeTestMethod(Invoker.java:820)
at org.testng.internal.Invoker.invokeTestMethods(Invoker.java:1128)
at org.testng.internal.TestMethodWorker.invokeTestMethods(TestMethodWorker.java:129)
at org.testng.internal.TestMethodWorker.run(TestMethodWorker.java:112)
at org.testng.TestRunner.privateRun(TestRunner.java:782)
at org.testng.TestRunner.run(TestRunner.java:632)
at org.testng.SuiteRunner.runTest(SuiteRunner.java:366)
at org.testng.SuiteRunner.runSequentially(SuiteRunner.java:361)
at org.testng.SuiteRunner.privateRun(SuiteRunner.java:319)
at org.testng.SuiteRunner.run(SuiteRunner.java:268)
at org.testng.SuiteRunnerWorker.runSuite(SuiteRunnerWorker.java:52)
at org.testng.SuiteRunnerWorker.run(SuiteRunnerWorker.java:86)
at org.testng.TestNG.runSuitesSequentially(TestNG.java:1244)
at org.testng.TestNG.runSuitesLocally(TestNG.java:1169)
at org.testng.TestNG.run(TestNG.java:1064)
at org.testng.IDEARemoteTestNG.run(IDEARemoteTestNG.java:74)
at org.testng.RemoteTestNGStarter.main(RemoteTestNGStarter.java:121)
at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
at java.lang.reflect.Method.invoke(Method.java:498)
at com.intellij.rt.execution.application.AppMain.main(AppMain.java:144)
Caused by: java.lang.InstantiationException: com.foobar.uitest.widgets.TheAbastractCellWidget is abstract so it can't be instantiated
at io.appium.java_client.pagefactory.OverrideWidgetReader.getConvenientClass(OverrideWidgetReader.java:65)
... 45 more

Link to Appium logs

no need

[truebit]

According to this page-object doc section "what-if-interaction-with-a-widget-has-special-details-for-each-used-platform-but-the-same-at-high-level". It seems that it's the restriction of OverrideWidget

[truebit]

After I followed the instruction in section what-if-interaction-with-a-widget-has-special-details-for-each-used-platform-but-the-same-at-high-level":
I moved iOSFindBy and AndroidFindBy annotations to the implementation class, the exception still exists. reopen.

[truebit]

I do not know the WidgetBuilder design. According to my trace of the code execution flow, OverrideWidget annotation element calls WidgetByBuilder's method to execute buildDefaultBy() first; which would got to getByFromDeclaredClass(WhatIsNeeded.DEFAULT_OR_HTML). This method would require the Wigdet class who must be not abstract.

According to the document mentioned above, an abstract widget class should be the correct way to use OverrideWidget. So I think this should be bug in the design

[truebit]

After several trace, I think I know the root cause:
OverrideWidget annotation must be specified with html argument. My case only contains androidUIAutomator and iOSUIAutomation.
If I assign html with any class in andorid or ios. it works...
IMO, OverrideWidget should support annotation without html assignment

[TikhomirovSergey]

Yes. I was apble to reproduce that issue. I'm going to fix it ASAP.