A guide to mocking objects with static methods...

AnalyticsBackEndProtocol.swift

protocol AnalyticsBackEnd {
    static func log(_ name: String)
}

extension Analytics: AnalyticsBackEnd {}

AnalyticsService.swift

class AnalyticsService {

    let backEnd: AnalyticsBackEnd.Type

    init(backEnd: AnalyticsBackEnd.Type = Analytics.self) {
        self.backEnd = backEnd
    }

    func log(event: String) {
        backEnd.log(event)
    }
}

AnalyticsUnitTest.swift

func testAnalyticsLogging() {
    let subject = AnalyticsService(backEnd: MockAnalyticsBackEnd.self)
    // Test...
}