junebash · July 29, 2020 23:45 · Jul 29, 2020
diff --git a/CodeChallengeTestCases.swift b/CodeChallengeTestCases.swift
@@ -0,0 +1,116 @@
+struct CodeChallengeTestCases<Input, Output> {
+   var title: String?
+   var expected: KeyValuePairs<Input, Output>
+   var solution: (Input) -> Output
+
+   init(
+      title: String? = nil,
+      expected: KeyValuePairs<Input, Output> = [:],
+      solution: @escaping (Input) -> Output)
+   {
+      self.title = title
+      self.expected = expected
+      self.solution = solution
+   }
+}
+
+extension CodeChallengeTestCases {
+   struct Failure {
+      let input: Input
+      let expectedOutput: Output
+      let actualOutput: Output
+
+      func print() {
+         Swift.print("Input:        \t\(input)\n"
+                  +  "Expected:     \t\(expectedOutput)\n"
+                  +  "Actual output:\t\(actualOutput)"
+         )
+      }
+   }
+
+   var isEmpty: Bool { expected.isEmpty }
+
+   func evaluate(_ outputEqualsExpected: (Output, Output) -> Bool) -> [Failure] {
+      expected.compactMap { ioPair -> Failure? in
+         let o = output(for: ioPair.key)
+         let e = ioPair.value
+
+         if outputEqualsExpected(o, e) {
+            return nil
+         } else {
+            return Failure(input: ioPair.key, expectedOutput: e, actualOutput: o)
+         }
+      }
+   }
+
+   func printFailures(_ outputEqualsExpected: (Output, Output) -> Bool) {
+      printFailures(evaluate(outputEqualsExpected))
+   }
+
+   func printFailures(_ failures: [Failure]) {
+      let titleText = title ?? "\(Input.self) -> \(Output.self)"
+
+      if failures.isEmpty {
+         print("All tests passed for '\(titleText)'!\n")
+         return
+      }
+
+      print("Tests failed for '\(titleText)':")
+      for f in failures {
+         printEvaluation(for: f.input,
+                         expected: f.expectedOutput,
+                         actual: f.actualOutput)
+      }
+      print("\n----------------\n")
+   }
+
+   func printEvaluations() {
+      expected.forEach { ioPair in
+         printEvaluation(for: ioPair.key,
+                         expected: ioPair.value,
+                         actual: solution(ioPair.key))
+      }
+   }
+}
+
+extension CodeChallengeTestCases where Output: Equatable {
+   func evaluate() -> [Failure] {
+      evaluate { $0 == $1 }
+   }
+
+   func printFailures() {
+      printFailures { $0 == $1 }
+   }
+}
+
+extension CodeChallengeTestCases {
+   private func output(for input: Input) -> Output {
+      solution(input)
+   }
+
+   private func printEvaluation(
+      for input: Input,
+      expected: Output,
+      actual: Output)
+   {
+      print("Input:        \t\(input)\n"
+         +  "Expected:     \t\(expected)\n"
+         +  "Actual output:\t\(actual)"
+      )
+   }
+}
+
+extension Array {
+   func print<I, O>() where Element == CodeChallengeTestCases<I, O>.Failure {
+      let titleText = "\(I.self) -> \(O.self)"
+
+      if self.isEmpty {
+         Swift.print("All tests passed for '\(titleText)'!\n")
+         return
+      }
+
+      Swift.print("Tests failed for '\(titleText)':")
+      self.forEach { $0.print() }
+      Swift.print("\n----------------\n")
+   }
+}