isEmpty triggers false-positive when using with XCUIElementQuery

[christiankm]

New Issue Checklist

• Updated SwiftLint to the latest version
• I searched for existing GitHub issues

Describe the bug

When trying to compare the cell count in a table from XCUITests, the isEmpty rule triggers, when we're using code like .cells.count > 0.

Problem is, that XCUIElementQuery.cells is not an array and has no isEmpty property, hence the false positive.

I would consider this a bug in SwiftFormat for now, though it would be more appropriate to add an isEmpty property so we can use that, to the XCTest framework.

Complete output when running SwiftLint, including the stack trace and command used

$ swiftlint lint

Environment

• SwiftLint version (run swiftlint version to be sure)? 0.52.2
• Installation method used (Homebrew, CocoaPods, building from source, etc)? Homebrew
• Paste your configuration file:

# insert yaml contents here

• Are you using nested configurations?
  If so, paste their relative paths and respective contents.
• Which Xcode version are you using (check xcodebuild -version)?
• Do you have a sample that shows the issue? Run echo "[string here]" | swiftlint lint --no-cache --use-stdin --enable-all-rules
  to quickly test if your example is really demonstrating the issue. If your example is more
  complex, you can use swiftlint lint --path [file here] --no-cache --enable-all-rules.

// This triggers a violation:
XCTAssertTrue(app.tables["table"].cells.count > 0)

[marcelofabri]

SwiftLint doesn't have enough information to tell if the underlying object has an isEmpty method - that's the reason why this rule isn't enabled by default.

See #827 for more discussion.