1  
 2  //              Copyright Catch2 Authors
 3  // Distributed under the Boost Software License, Version 1.0.
 4  //   (See accompanying file LICENSE.txt or copy at
 5  //        https://www.boost.org/LICENSE_1_0.txt)
 6  
 7  // SPDX-License-Identifier: BSL-1.0
 8  
 9  // 302-Gen-Table.cpp
10  // Shows how to use table to run a test many times with different inputs. Lifted from examples on
11  // issue #850.
12  
13  #include <catch2/catch_test_macros.hpp>
14  #include <catch2/generators/catch_generators.hpp>
15  #include <string>
16  
17  struct TestSubject {
18      // this is the method we are going to test. It returns the length of the
19      // input string.
20      size_t GetLength( const std::string& input ) const { return input.size(); }
21  };
22  
23  
24  TEST_CASE("Table allows pre-computed test inputs and outputs", "[example][generator]") {
25      using std::make_tuple;
26      // do setup here as normal
27      TestSubject subj;
28  
29      SECTION("This section is run for each row in the table") {
30          std::string test_input;
31          size_t expected_output;
32          std::tie( test_input, expected_output ) =
33              GENERATE( table<std::string, size_t>(
34                  { /* In this case one of the parameters to our test case is the
35                     * expected output, but this is not required. There could be
36                     * multiple expected values in the table, which can have any
37                     * (fixed) number of columns.
38                     */
39                    make_tuple( "one", 3 ),
40                    make_tuple( "two", 3 ),
41                    make_tuple( "three", 5 ),
42                    make_tuple( "four", 4 ) } ) );
43  
44          // run the test
45          auto result = subj.GetLength(test_input);
46          // capture the input data to go with the outputs.
47          CAPTURE(test_input);
48          // check it matches the pre-calculated data
49          REQUIRE(result == expected_output);
50      }   // end section
51  }
52  
53  /* Possible simplifications where less legacy toolchain support is needed:
54   *
55   * - With libstdc++6 or newer, the make_tuple() calls can be omitted
56   * (technically C++17 but does not require -std in GCC/Clang). See
57   *   https://stackoverflow.com/questions/12436586/tuple-vector-and-initializer-list
58   *
59   * - In C++17 mode std::tie() and the preceding variable declarations can be
60   * replaced by structured bindings: auto [test_input, expected] = GENERATE(
61   * table<std::string, size_t>({ ...
62   */
63  // Compiling and running this file will result in 4 successful assertions