Tests: Use ES6 class syntax for inheritance in calendarFixtures.js

[Copilot]

Replaces the legacy Class.inherit() pattern with ES6 class/extends syntax in testing/helpers/calendarFixtures.js, and removes the unused MockMonthView class along with the unrecognized monthViewType option.

Changes

• BaseCalendarFixture: Class.inherit({...}) → class BaseCalendarFixture { ... }
• CalendarFixture / DateBoxFixture: .inherit({ctor: function(){...}}) → class X extends BaseCalendarFixture with proper constructor
• Removed MockMonthView: The class overrode renderHeader/renderBody (wrong method names — the actual implementation uses _renderHeader/_renderBody), and monthViewType was never a recognized option in dxCalendar or dxDateBox, so the mock was never invoked
• Removed monthViewType from both CalendarFixture and DateBoxFixture constructors (unrecognized option)
• Removed imports: Class (from core/class), noop (from core/utils/common), and Views (from calendar.views) are no longer needed
• Global assignments: Replaced $.extend(true, DevExpress.ui, {...}) blocks with direct property assignments to preserve backward compatibility with consumers using DevExpress.ui.testing.*

Before / After

// Before
BaseCalendarFixture: Class.inherit({
    ctor: function(options) { ... },
    dispose: function() { ... }
})

// After
class BaseCalendarFixture {
    constructor(options) { ... }
    dispose() { ... }
}
DevExpress.ui.testing.BaseCalendarFixture = BaseCalendarFixture;

Original prompt

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This section details on the original issue you should resolve

<issue_title>Tests: Use ES6 syntax for inheritance in packages/devextreme/testing/helpers/calendarFixtures.js</issue_title>
<issue_description></issue_description>

Comments on the Issue (you are @copilot in this section)

• Fixes DevExpress/devextreme-private#3584

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[Copilot]

Pull request overview

Refactors the calendar testing fixtures to use native ES6 class/extends syntax instead of the legacy Class.inherit() pattern, while keeping the fixtures available via the DevExpress.ui.testing.* global namespace for existing tests.

Changes:

• Replaced Class.inherit()-based fixtures with ES6 classes (BaseCalendarFixture, CalendarFixture, DateBoxFixture).
• Replaced Views['month'].inherit(...) with an ES6 subclass (MockMonthView).
• Switched from $.extend(true, DevExpress.ui, { testing: ... }) to direct DevExpress.ui.testing.* assignments.

[r-farkhutdinov]

@copilot fix the notes

[Copilot]

@copilot fix the notes

Fixed in 62d0c44:

• Removed MockMonthView entirely — it was overriding renderHeader/renderBody (wrong names; the actual calendar uses _renderHeader/_renderBody) and was never actually invoked since monthViewType is not a recognized option in either dxCalendar or dxDateBox.
• Removed the monthViewType option from both CalendarFixture and DateBoxFixture constructors.
• Removed the now-unused Views import.

[Copilot]

Pull request overview

Copilot reviewed 1 out of 1 changed files in this pull request and generated no new comments.