[test] Drop stdlib-redundant tests

hasPrefix/hasSuffix is now available universally from the standard
library (it used to be Darwin only). As such, these tests are
redundant with the tests in the standard library (indeed they are
literally copy-pasted from the stdlib). As test methodology changes,
maintaining these across projects and platforms is troublesome.

Author: milseman

TestFoundation/TestNSString.swift

@@ -1210,225 +1210,6 @@ class TestNSString : XCTestCase {
     }
 }
 
-struct ComparisonTest {
-    enum TestBehavior {
-      case run
-      case expectedFailure(String)
-      case skip(String)
-    }
-    let lhs: String
-    let rhs: String
-    let loc: UInt
-    let behavior: TestBehavior
-
-    var expectedFailure: Bool {
-      if case .expectedFailure = behavior {
-        return true
-      } else {
-        return false
-      }
-    }
-
-    init(
-      _ lhs: String, _ rhs: String,
-      expectedFailure xfailReason: String = "",
-      skip skipReason: String = "",
-      line: UInt = #line
-      ) {
-      self.lhs = lhs
-      self.rhs = rhs
-      self.loc = line
-    
-      switch (xfailReason.isEmpty, skipReason.isEmpty) {
-      case (false, true):
-        behavior = .expectedFailure(xfailReason)
-      case (_, false):
-        behavior = .skip(skipReason)
-      default:
-        behavior = .run
-      }
-    }
-}
-
-let comparisonTests: [ComparisonTest] = [
-    ComparisonTest("", ""),
-    ComparisonTest("", "a"),
-
-    // ASCII cases
-    ComparisonTest("t", "tt"),
-    ComparisonTest("t", "Tt"),
-    ComparisonTest("\u{0}", "",
-        skip: "rdar://problem/37686816"),
-    ComparisonTest("\u{0}", "\u{0}",
-        expectedFailure: "https://bugs.swift.org/browse/SR-332"),
-    ComparisonTest("\r\n", "t"),
-    ComparisonTest("\r\n", "\n",
-        expectedFailure: "blocked on rdar://problem/19036555"),
-    ComparisonTest("\u{0}", "\u{0}\u{0}",
-        expectedFailure: "rdar://problem/19034601"),
-
-    // Whitespace
-    // U+000A LINE FEED (LF)
-    // U+000B LINE TABULATION
-    // U+000C FORM FEED (FF)
-    // U+0085 NEXT LINE (NEL)
-    // U+2028 LINE SEPARATOR
-    // U+2029 PARAGRAPH SEPARATOR
-    ComparisonTest("\u{0085}", "\n"),
-    ComparisonTest("\u{000b}", "\n"),
-    ComparisonTest("\u{000c}", "\n"),
-    ComparisonTest("\u{2028}", "\n"),
-    ComparisonTest("\u{2029}", "\n"),
-    ComparisonTest("\r\n\r\n", "\r\n"),
-
-    // U+0301 COMBINING ACUTE ACCENT
-    // U+00E1 LATIN SMALL LETTER A WITH ACUTE
-    ComparisonTest("a\u{301}", "\u{e1}"),
-    ComparisonTest("a", "a\u{301}"),
-    ComparisonTest("a", "\u{e1}"),
-
-    // U+304B HIRAGANA LETTER KA
-    // U+304C HIRAGANA LETTER GA
-    // U+3099 COMBINING KATAKANA-HIRAGANA VOICED SOUND MARK
-    ComparisonTest("\u{304b}", "\u{304b}"),
-    ComparisonTest("\u{304c}", "\u{304c}"),
-    ComparisonTest("\u{304b}", "\u{304c}"),
-    ComparisonTest("\u{304b}", "\u{304c}\u{3099}"),
-    ComparisonTest("\u{304c}", "\u{304b}\u{3099}"),
-    ComparisonTest("\u{304c}", "\u{304c}\u{3099}"),
-
-    // U+212B ANGSTROM SIGN
-    // U+030A COMBINING RING ABOVE
-    // U+00C5 LATIN CAPITAL LETTER A WITH RING ABOVE
-    ComparisonTest("\u{212b}", "A\u{30a}"),
-    ComparisonTest("\u{212b}", "\u{c5}"),
-    ComparisonTest("A\u{30a}", "\u{c5}"),
-    ComparisonTest("A\u{30a}", "a"),
-    ComparisonTest("A", "A\u{30a}"),
-
-    // U+2126 OHM SIGN
-    // U+03A9 GREEK CAPITAL LETTER OMEGA
-    ComparisonTest("\u{2126}", "\u{03a9}"),
-
-    // U+0323 COMBINING DOT BELOW
-    // U+0307 COMBINING DOT ABOVE
-    // U+1E63 LATIN SMALL LETTER S WITH DOT BELOW
-    // U+1E69 LATIN SMALL LETTER S WITH DOT BELOW AND DOT ABOVE
-    ComparisonTest("\u{1e69}", "s\u{323}\u{307}"),
-    ComparisonTest("\u{1e69}", "s\u{307}\u{323}"),
-    ComparisonTest("\u{1e69}", "\u{1e63}\u{307}"),
-    ComparisonTest("\u{1e63}", "s\u{323}"),
-    ComparisonTest("\u{1e63}\u{307}", "s\u{323}\u{307}"),
-    ComparisonTest("\u{1e63}\u{307}", "s\u{307}\u{323}"),
-    ComparisonTest("s\u{323}", "\u{1e69}"),
-
-    // U+FB01 LATIN SMALL LIGATURE FI
-    ComparisonTest("\u{fb01}", "\u{fb01}"),
-    ComparisonTest("fi", "\u{fb01}"),
-
-    // U+1F1E7 REGIONAL INDICATOR SYMBOL LETTER B
-    // \u{1F1E7}\u{1F1E7} Flag of Barbados
-    ComparisonTest("\u{1F1E7}", "\u{1F1E7}\u{1F1E7}"),
-
-    // Test that Unicode collation is performed in deterministic mode.
-    //
-    // U+0301 COMBINING ACUTE ACCENT
-    // U+0341 COMBINING ACUTE TONE MARK
-    // U+0954 DEVANAGARI ACUTE ACCENT
-    //
-    // Collation elements from DUCET:
-    // 0301  ; [.0000.0024.0002] # COMBINING ACUTE ACCENT
-    // 0341  ; [.0000.0024.0002] # COMBINING ACUTE TONE MARK
-    // 0954  ; [.0000.0024.0002] # DEVANAGARI ACUTE ACCENT
-    //
-    // U+0301 and U+0954 don't decompose in the canonical decomposition mapping.
-    // U+0341 has a canonical decomposition mapping of U+0301.
-    ComparisonTest("\u{0301}", "\u{0341}"),
-    ComparisonTest("\u{0301}", "\u{0954}"),
-    ComparisonTest("\u{0341}", "\u{0954}"),
-]
-
-enum Stack: Swift.Error {
-    case Stack([UInt])
-}
-
-func checkHasPrefixHasSuffix(_ lhs: String, _ rhs: String, _ stack: [UInt]) -> Int {
-    if (lhs == "" && rhs == "") {
-        var failures = 0
-        failures += lhs.hasPrefix(rhs) ? 0: 1
-        failures += lhs.hasSuffix(rhs) ? 0: 1
-        return failures
-    } else if lhs == "" {
-        var failures = 0
-        failures += lhs.hasPrefix(rhs) ? 1 : 0
-        failures += lhs.hasSuffix(rhs) ? 1 : 0
-        return failures
-    } else if rhs == "" {
-        var failures = 0
-        failures += lhs.hasPrefix(rhs) ? 0 : 1 
-        failures += lhs.hasSuffix(rhs) ? 0 : 1 
-        return failures
-    }
-
-    // To determine the expected results, compare grapheme clusters,
-    // scalar-to-scalar, of the NFD form of the strings.
-    let lhsNFDGraphemeClusters =
-        lhs.decomposedStringWithCanonicalMapping.map {
-            Array(String($0).unicodeScalars)
-    }
-    let rhsNFDGraphemeClusters =
-        rhs.decomposedStringWithCanonicalMapping.map {
-            Array(String($0).unicodeScalars)
-    }
-    let expectHasPrefix = lhsNFDGraphemeClusters.starts(
-        with: rhsNFDGraphemeClusters, by: (==))
-    let expectHasSuffix =
-        lhsNFDGraphemeClusters.lazy.reversed().starts(
-            with: rhsNFDGraphemeClusters.lazy.reversed(), by: (==))
-
-    func testFailure(_ lhs: Bool, _ rhs: Bool, _ stack: [UInt]) -> Int {
-        guard lhs == rhs else {
-            // print(stack)
-            return 1
-        }
-        return 0
-    }
-
-    var failures = 0
-    failures += testFailure(expectHasPrefix, lhs.hasPrefix(rhs), stack + [#line])
-    failures += testFailure(expectHasSuffix, lhs.hasSuffix(rhs), stack + [#line])
-    return failures
-}
-
-extension TestNSString {
-    func test_PrefixSuffix() {
-        for test in comparisonTests {
-            if case .skip = test.behavior {
-              continue
-            }
-          
-            var failures = 0
-            failures += checkHasPrefixHasSuffix(test.lhs, test.rhs, [test.loc, #line])
-            failures += checkHasPrefixHasSuffix(test.rhs, test.lhs, [test.loc, #line])
-
-            let fragment = "abc"
-            let combiner = "\u{0301}"
-
-            failures += checkHasPrefixHasSuffix(test.lhs + fragment, test.rhs, [test.loc, #line])
-            failures += checkHasPrefixHasSuffix(fragment + test.lhs, test.rhs, [test.loc, #line])
-            failures += checkHasPrefixHasSuffix(test.lhs + combiner, test.rhs, [test.loc, #line])
-            failures += checkHasPrefixHasSuffix(combiner + test.lhs, test.rhs, [test.loc, #line])
-
-            let fail = (failures > 0)
-            if fail {
-                // print("Prefix/Suffix case \(test.loc): \(failures) failures")
-                // print("Failures were\(test.expectedFailure ? "" : " not") expected")
-            }
-            XCTAssert(test.expectedFailure == fail, "Unexpected \(test.expectedFailure ?"success":"failure"): \(test.loc)")
-        }
-    }
-}
-
 func test_reflection() {
 }