catch2/examples/302-Gen-Table.cpp

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// 302-Gen-Table.cpp
// Shows how to use table to run a test many times with different inputs. Lifted from examples on
// issue #850.
#include <catch2/catch.hpp>
#include <string>
struct TestSubject {
// this is the method we are going to test. It returns the length of the
// input string.
size_t GetLength( const std::string& input ) const { return input.size(); }
};
TEST_CASE("Table allows pre-computed test inputs and outputs", "[example][generator]") {
using std::make_tuple;
// do setup here as normal
TestSubject subj;
SECTION("This section is run for each row in the table") {
std::string test_input;
size_t expected_output;
std::tie( test_input, expected_output ) =
GENERATE( table<std::string, size_t>(
{ /* In this case one of the parameters to our test case is the
* expected output, but this is not required. There could be
* multiple expected values in the table, which can have any
* (fixed) number of columns.
*/
make_tuple( "one", 3 ),
make_tuple( "two", 3 ),
make_tuple( "three", 5 ),
make_tuple( "four", 4 ) } ) );
// run the test
auto result = subj.GetLength(test_input);
// capture the input data to go with the outputs.
CAPTURE(test_input);
// check it matches the pre-calculated data
REQUIRE(result == expected_output);
} // end section
}
/* Possible simplifications where less legacy toolchain support is needed:
*
* - With libstdc++6 or newer, the make_tuple() calls can be omitted
* (technically C++17 but does not require -std in GCC/Clang). See
* https://stackoverflow.com/questions/12436586/tuple-vector-and-initializer-list
*
* - In C++17 mode std::tie() and the preceeding variable delcarations can be
* replaced by structured bindings: auto [test_input, expected] = GENERATE(
* table<std::string, size_t>({ ...
*/
// Compiling and running this file will result in 4 successful assertions