-- The TestSuiteSupportModule defines a new type, a TestItem, that
-- can be used to organize and display single tests and test suites.
-- The display for each single test or each test case in a test suite
-- includes a description of the test and whether it passed or failed.
--
-- Use the TestSuite constructor to create a test suite object,
-- providing a description of the test suite and a list of test
-- items (single tests or nested test suites).  Use the Test
-- constructor to make a test item out of a boolean expression, again
-- providing a description.  The boolean expression should evaluate
-- to True when the test it represents passes.
-- For example, 
--    example1 = TestSuite "An empty test suite" []
--    example2 = TestSuite "A suite with a single test"
--                         [ Test "test1" boolExpr ]
--       -- where boolExpr is some boolean expression such as
--       --   (callToFunctionToTest == expectedResult)
--       -- Example:
--           concreteEx2 = TestSuite "Concrete suite with single test"
--                            [ Test "The test" (reverse [1, 2] == [2, 1]) ]
--    example3 = TestSuite "A suite with multiple tests"
--               [ Test "1" boolExpr1, Test "2" boolExpr2, Test "3" boolExpr3 ]
--    example4 = TestSuite "A suite with tests and nested suites"
--                 [ Test "test1" boolExpr1, example1, example2 ]
-- In these examples, the identifiers example1, ..., example4 are
-- zero-parameter functions that each evaluate to a specific test suite.
--
-- To run a test suite and display its results, simply type the
-- identifier associated with the test suite.  For example,
-- typing
--      concreteEx2
-- would show the following results:
--      Concrete suite with single test
--        The test: Passed
--
-- This module also defines the runTest function which evaluates
-- to a single boolean value representing whether the test passed
-- or not.  If the test item passed to runTest is an entire test
-- suite, the function returns True if all the tests passed, in
-- other words, if all the tests in the suite evaluated to True,
-- and returns False if any test in the suite failed.
-- For example,
--    runTest example3
-- would return true if all three tests in the suite passed.
--
-- Author: Alyce Brady
--
-- November 2003

module TestSuiteSupportModule(TestItem(Test, TestSuite), runTest) where

-----------------------------------------------
-----------------------------------------------
-- TYPES AND FUNCTIONS TO SUPPORT UNIT TESTING
-----------------------------------------------
-----------------------------------------------

type Description = String

data TestItem = Test Description Bool | TestSuite Description [ TestItem ]

instance Show TestItem where
    show testItem = showFormatted testItem ""
      where
        -----------------------------------------------
        -- showFormatted testItem indentation
        --    Evaluates the specified test item and
        --    displays the formatted results.
        -----------------------------------------------
        showFormatted :: TestItem -> String -> String
        showFormatted (Test description test) indentation =
            indentation ++ description ++ ": " ++
                           (if test then "Passed" else "Failed")
        showFormatted (TestSuite description []) indentation =
            indentation ++ description
        showFormatted (TestSuite description testList ) indentation =
            indentation ++ description ++ 
                           (showListResults testList (indentation ++ "  "))
          where
              -----------------------------------------------
              -- showListResults listOfTests indentation
              --    Shows the results for a list of test suite elements.
              -----------------------------------------------
              showListResults :: [ TestItem ] -> String -> String
              showListResults [ ] indentation = ""
              showListResults ( firstTest : rest ) indentation =
                  "\n" ++ (showFormatted firstTest indentation) ++
                  (showListResults rest indentation)

-----------------------------------------------
-- runTest testItem
--    Tests the specified test item, which may
--    be a single test or a test suite.
--    Returns true if the test or all tests in
--    the suite passed, and false otherwise.
-----------------------------------------------
runTest :: TestItem -> Bool
runTest (Test _ singleTest) = singleTest
runTest (TestSuite _ []) = True
runTest (TestSuite _ testSuite) = and (map runTest testSuite)


---------------------------------------------------
---------------------------------------------------
-- TEST CASES TO TEST THE TEST SUITE SUPPORT MODULE
---------------------------------------------------
---------------------------------------------------

emptyTestSuite =
  TestSuite "An empty test suite..." [ ]

nonEmptyTestSuite =
  TestSuite "A non-empty test suite..." [ Test "A true test" True ]

testTestSuite =
  TestSuite "Test a test suite with multiple nested suites..."
  [
      TestSuite "Testing a single, empty, nested test suite" [],
      TestSuite "Testing suite with a single test..."
                           [ Test "A true test" True ],
      TestSuite "Testing suite with multiple tests..."
              [ Test "A true test" True, Test "Another true test" True ],
      TestSuite "Testing a suite containing a single suite"
              [ TestSuite "The nested test suite"
                           [ Test "The test in the nested suite" True ] ],
      TestSuite "Testing a mix of tests and test suites..."
              [ TestSuite "The first nested test suite"
                           [ Test "A nested single test" True,
                             emptyTestSuite,
                             nonEmptyTestSuite
                           ],
                Test "A single test" True,
                TestSuite "Another nested test suite"
                           [ Test "Another nested single test" True,
                             nonEmptyTestSuite,
                             emptyTestSuite
                           ],
                Test "Another single test" True
              ],
      Test "Placeholder test" True
  ]