lest – lest errors escape testing

This tiny C++11 test helper is based on ideas and examples by Kevlin Henney [1,2] and on ideas found in the CATCH test framework by Phil Nash [3].

Let writing tests become irresistibly easy and attractive.

Contents

• Example usage
• Compile and run
• Synopsis
• Reported to work with
• Variants of lest
• Notes and References

Example usage

#include "lest.hpp"

using namespace std;

const lest::test specification[] =
{
    "Empty string has length zero (succeed)", []
    {
        EXPECT( 0 == string(  ).length() );
        EXPECT( 0 == string("").length() );
    },

    "Text compares lexically (fail)", []
    {
        EXPECT( string("hello") > string("world") );
    },

    "Unexpected exception is reported", []
    {
        EXPECT( (throw std::runtime_error("surprise!"), true) );
    },

    "Unspecified expected exception is captured", []
    {
        EXPECT_THROWS( (throw std::runtime_error("surprise!"), true) );
    },

    "Specified expected exception is captured", []
    {
        EXPECT_THROWS_AS( (throw std::bad_alloc(), true), std::bad_alloc );
    },

    "Expected exception is reported missing", []
    {
        EXPECT_THROWS( true );
    },

    "Specific expected exception is reported missing", []
    {
        EXPECT_THROWS_AS( true, std::runtime_error );
    },
};

int main()
{
    return lest::run( specification );
}

Compile and run

prompt>g++ -Wall -Wextra -Weffc++ -std=c++11 -o example1.exe example1.cpp && example1
example1.cpp:16: failed: Text compares lexically (fail): string("hello") > string("world")
example1.cpp:21: failed: got unexpected exception with message "surprise!": Unexpected exception is reported: (throw std::runtime_error("surprise!"), true)
example1.cpp:36: failed: didn't get exception: Expected exception is reported missing: true
example1.cpp:41: failed: didn't get exception of type std::runtime_error: Specific expected exception is reported missing: true
4 out of 7 tests failed.

Synopsis

Assertions Macros

EXPECT( expr )
Evaluate the expression and report failure. If an exception is thrown it is caught, reported and counted as a failure.

EXPECT_THROWS( expr )
Expect that an exception (of any type) is thrown during evaluation of the expression.

EXPECT_THROWS_AS( expr, exception )
Expect that an exception of the specified type is thrown during evaluation of the expression.

If an assertion fails, the remainder of the test that assertion is part of is skipped.

Note that EXPECT(), EXPECT_THROWS() and EXPECT_THROWS_AS() are shortened aliases for lest_EXPECT(), lest_EXPECT_THROWS() and lest_EXPECT_THROWS_AS().

Other Macros

lest_NO_SHORT_ASSERTION_NAMES
Define this to omit the shortened alias macros for the lest_EXPECT... macros.

Namespace

namespace lest { }
Types and functions are located in namespace lest.

Tests

struct test
{
 const std::string name;
 const std::function<void()> behaviour;
};

Functions

template<std::size_t N>
int run( test const (& specification )[N], std::ostream & os = std::cout )

• specification - array of tests
• os - stream to report to
• returns number of failing tests

Reported to work with

• clang 3.2
• g++ 4.6, 4.8.1
• Visual Studio 2013 preview

Variants of lest

The variants of lest here are meant to stay as simple as they are now, so that they provide an easy read into the techniques used and remain the tiny test frameworks that are a good fit to include with small projects.

You are encouraged to take it from here and change and expand it as you see fit and publish your variant. If you do, I'd much appreciate to hear from you!

• lest with groups - Pavel Medvedev
• lest with expression decomposition - lest_decompose.hpp, this project [1].
• lest for C++03 with expression decomposition - lest_cpp03.hpp, this project [1].
• hamlest - matchers for lest.

Notes and References

[1] Kevlin Henney on Rethinking Unit Testing in C++ (Video).

[2] Martin Moene. Elefant C++11 test setup on the ACCU mailing list accu-general (requires login). It mentions the C++11 test appoach Andrzej Krzemieński uses for Optional. A library for optional (nullable) objects for C++11.

[3] Phil Nash. CATCH, an automated test framework for C, C++ and Objective-C.

[4] A more technically informed name: lest - lambda engaged small tester.