Remove legacy LexTests

These are all tested by `diagnosticTest` now.

Author: hamishknight

Tests/RegexTests/LexTests.swift

@@ -14,91 +14,7 @@
 import XCTest
 @testable import _StringProcessing
 
-func diagnose(
-  _ input: String,
-  expecting expected: ParseError,
-  _ syntax: SyntaxOptions = .traditional,
-  _ f: (inout Source) throws -> (),
-  file: StaticString = #file,
-  line: UInt = #line
-) {
-  var src = Source(input)
-  do {
-    try f(&src)
-    XCTFail("""
-      Passed, but expected error: \(expected)
-    """, file: file, line: line)
-  } catch let e as Source.LocatedError<ParseError> {
-    guard e.error == expected else {
-      XCTFail("""
-
-        Expected: \(expected)
-        Actual: \(e.error)
-      """, file: file, line: line)
-      return
-    }
-  } catch let e {
-    fatalError("Should be unreachable: \(e)")
-  }
-}
-
 extension RegexTests {
-  func testLexicalAnalysis() {
-    diagnose("a", expecting: .expected("b")) { src in
-      try src.expect("b")
-    }
-
-    diagnose("", expecting: .unexpectedEndOfInput) { src in
-      try src.expectNonEmpty()
-    }
-    diagnose("a", expecting: .unexpectedEndOfInput) { src in
-      try src.expect("a") // Ok
-      try src.expectNonEmpty() // Error
-    }
-
-    let bigNum = "12345678901234567890"
-    diagnose(bigNum, expecting: .numberOverflow(bigNum)) { src in
-      _ = try src.lexNumber()
-    }
-
-    func diagnoseUniScalarOverflow(_ input: String, base: Character) {
-      let scalars = input.first == "{"
-                  ? String(input.dropFirst().dropLast())
-                  : input
-      diagnose(
-        input,
-        expecting: .numberOverflow(scalars)
-      ) { src in
-        _ = try src.expectUnicodeScalar(escapedCharacter: base)
-      }
-    }
-    func diagnoseUniScalar(
-      _ input: String,
-      base: Character,
-      expectedDigits numDigits: Int
-    ) {
-      let scalars = input.first == "{"
-                  ? String(input.dropFirst().dropLast())
-                  : input
-      diagnose(
-        input,
-        expecting: .expectedNumDigits(scalars, numDigits)
-      ) { src in
-        _ = try src.expectUnicodeScalar(escapedCharacter: base)
-      }
-      _ = scalars
-    }
-
-    diagnoseUniScalar(
-      "12", base: "u", expectedDigits: 4)
-    diagnoseUniScalar(
-      "12", base: "U", expectedDigits: 8)
-    diagnoseUniScalarOverflow("{123456789}", base: "u")
-    diagnoseUniScalarOverflow("{123456789}", base: "x")
-
-    // TODO: want to dummy print out source ranges, etc, test that.
-  }
-
 
   func testCompilerInterface() throws {
     func delim(_ kind: Delimiter.Kind, poundCount: Int = 0) -> Delimiter {