string concat benchmarks

StringsTest.swift

import XCTest

// Tweet link: https://twitter.com/nicklockwood/status/972215130825154561

let count = 50000

class StringsTestTests: XCTestCase {
  
  // Tweet link: https://twitter.com/cocoaphony/status/972227239914942474
  func testNoMutate() {
    var foo = ""
    measure {
      foo = "foo" + repeatElement("bar", count: count).joined()
    }
    print(foo)
  }
  
  // MARK: Copying
  func testInterpolation() {
    var foo = ""
    measure {
      foo = "foo"
      for _ in 0 ..< count {
        foo = "\(foo)bar"
      }
    }
    print(foo)
  }
  
  func testPlusOperator() {
    var foo = ""
    measure {
      foo = "foo"
      for _ in 0 ..< count {
        foo = foo + "bar"
      }
    }
    print(foo)
  }
  
  func testAppending() {
    var foo = ""
    measure {
      foo = "foo"
      for _ in 0 ..< count {
        foo = foo.appending("bar")
      }
    }
    print(foo)
  }
  
  // MARK: Mutating
  func testPlusEquals() {
    var foo = ""
    measure {
      foo = "foo"
      for _ in 0 ..< count {
        foo += "bar"
      }
    }
    print(foo)
  }
  
  func testAppend() {
    var foo = ""
    measure {
      foo = "foo"
      for _ in 0 ..< count {
        foo.append("bar")
      }
    }
    print(foo)
  }
}