SetUnionTests.swift

import XCTest
@testable import SetUnion

final class SetUnionTests: XCTestCase {
  let a1: [Set<Int>?] = [[1, 2], [2, 3], nil]
  let n = 100000

  func testX1 () {
    self.measure {
      for _ in 1...self.n {
        _ = Set(self.a1.flatMap { $0 ?? [] })
      }
    }
  }

  func testX2 () {
    self.measure {
      for _ in 1...self.n {
        _ = self.a1.reduce(Set<Int>()) { $0.union($1 ?? []) }
      }
    }
  }

  func testX3 () {
    self.measure {
      for _ in 1...self.n {
        _ = self.a1.reduce(into: Set<Int>()) { $0.formUnion($1 ?? []) }
      }
    }
  }

  func testX4 () {
    self.measure {
      for _ in 1...self.n {
        var x4 = Set<Int>()

        for set in a1 {
          x4.formUnion(set ?? [])
        }
      }
    }
  }

  func testX5 () {
    self.measure {
      for _ in 1...self.n {
        var x5 = Set<Int>()

        a1.forEach { x5.formUnion($0 ?? []) }
      }
    }
  }

  func testX6 () {
    self.measure {
      for _ in 1...self.n {
        _ = Set(a1.compactMap { $0 }.flatMap { $0 })
      }
    }
  }
}