UTF8Tests.swift

import Parsing
import XCTest

final class UTF8Tests: XCTestCase {
  func testSubstringNormalization() {
    var input = "\u{00E9}e\u{0301}e\u{0341} Hello, world"[...].utf8
    let parser = From<Conversions.UTF8ViewToSubstring, Substring, String>(.substring) { "é" }
    XCTAssertNoThrow(try parser.parse(&input))
    XCTAssertEqual("e\u{0301}e\u{0341} Hello, world", Substring(input))
    XCTAssertNoThrow(try parser.parse(&input))
    XCTAssertEqual("e\u{0341} Hello, world", Substring(input))
    XCTAssertNoThrow(try parser.parse(&input))
    XCTAssertEqual(" Hello, world", Substring(input))
    XCTAssertThrowsError(try parser.parse(&input)) { error in
      XCTAssertEqual(
        """
        error: unexpected input
         --> input:1:4
        1 | ééé Hello, world
          |    ^ expected "é"
        """,
        "\(error)"
      )
    }
    XCTAssertEqual(" Hello, world", Substring(input))
  }

  func testUnicodeScalars() {
    var input = "🇺🇸 Hello, world"[...].unicodeScalars
    let parser = "🇺".unicodeScalars
    XCTAssertNoThrow(try parser.parse(&input))
    XCTAssertEqual("🇸 Hello, world", Substring(input))
    XCTAssertThrowsError(try parser.parse(&input)) { error in
      XCTAssertEqual(
        """
        error: unexpected input
         --> input:1:1
        1 | 🇺🇸 Hello, world
          | ^ expected "🇺"
        """,
        "\(error)"
      )
    }
    XCTAssertEqual("🇸 Hello, world", Substring(input))
  }

  func testUTF8Normalization() {
    enum City {
      case losAngeles
      case newYork
      case sanJose
    }

    let city = OneOf {
      "Los Angeles".utf8.map { City.losAngeles }
      "New York".utf8.map { City.newYork }
      "San Jos\u{00E9}".utf8.map { City.sanJose }
    }

    XCTAssertThrowsError(try city.parse("San Jose\u{0301}")) { error in
      XCTAssertEqual(
        """
        error: unexpected input
         --> input:1:1
        1 | San José
          | ^ expected "Los Angeles"
          | ^ expected "New York"
          | ^ expected "San José"
        """,
        "\(error)"
      )
    }
  }
}