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Experiments with testing in C++. Testinator is a unit testing framework. It is known to work with:

  • Clang 3.4/libc++
  • Clang 3.7/libc++
  • GCC 4.9/libstdc++
  • GCC 5.0/libstdc++
  • MSVC 2015 Update 1


Build Status Build status Coverage Status

Testinator is distributed under the MIT license. See LICENSE for details.

Basic setup

Testinator is a header-only library. To use it in the simplest way, a complete program is:

#include <testinator.h>

This includes everything you need and provides a main function with some command line parameters:

Usage: testinator [OPTION]...
Run all tests in randomized order by default.

--testName=NAME    run only the named test
--suiteName=NAME   run only the tests in the named suite
--alpha            run tests in alphabetical order
--output=FORMAT    use the specified output formatter, e.g. TAP
--verbose          give verbose output (according to formatter)
--nocolor          output without ANSI color codes (according to formatter)
--numChecks=N      number of checks to use for property tests
--seed=SEED        use SEED for property test randomization

Simple usage

Ordinary unit tests are grouped into suites and defined with a macro (arguments: test name and suite name) and function body which should return true if the test is successful, false otherwise.

DEF_TEST(TestName, SuiteName)
  // your logic here...
  return success;

You can use the EXPECT macro to test conditions in a way that will output the condition on failure:

bool b = true;
EXPECT(!b == b);

Produces the output:

EXPECT FAILED: <file>:<line> (!b == b => false == true)

The DIAGNOSTIC macro produces arbitrary diagnostic output:

DIAGNOSTIC("Hello world " << 42);

Critical failures

Ordinarily, a test should return true or false to indicate success or failure. If a test has a problem that means it should be skipped, you can use SKIP to skip that test:

DEF_TEST(TestName, SuiteName)
  // this test went wrong in some deep way
  SKIP("Something bad happened");
  return true;

And if a test has such a problem that no other tests are likely to succeed, you can use ABORT to bail out completely:

DEF_TEST(TestName, SuiteName)
  // critical failure, don't run any more tests
  ABORT("Self destruct");
  return true;

After SKIP or ABORT it doesn't matter what is returned.


Instead of exposing fixtures or setup/teardown functionality, Testinator uses the idea of Branches. Branches are subsections of tests that will be executed on successive runs of the test. This allows fixtures to be replaced with more natural scoping. Branches are introduced with the BRANCH macro and their name may be retrieved with BRANCH_NAME. For example:

DEF_TEST(TestName, SuiteName)
  // some common setup here...
  bool success = true;

    // this executes first time around
    DIAGNOSTIC("In branch " << BRANCH_NAME);

    // this executes second time around
    DIAGNOSTIC("In branch " << BRANCH_NAME);

  return success;

Branches may be nested if further common structure is required; the test will run as many times as necessary to visit all the "leaves". If Branches are not explicitly named, BRANCH_NAME will be automatically provided with filename and line information.

If a test returns early (assumedly with a failure, returning false) from within a Branch, this will cause subsequent Branches to be skipped.


Testinator also supports properties: invariants that hold true for your algorithms.

Properties are defined the same way as tests, just with a different macro and additional parameters that are the function arguments. (One argument is the usual case, shown here.)

DEF_PROPERTY(StringReverse, Algos, const string& s)
  string r(s);
  reverse(r.begin(), r.end());
  reverse(r.begin(), r.end());
  return s == r;

Testinator will generate arbitrary values of the arguments and feed them to your test.


Testinator knows how to generate values of standard types, but if you have a type that you've defined, you may need to tell Testinator how to generate it. To do this, specialize the Arbitrary template. Examples are in arbitrary_*.h and property.cpp. The output operator, operator<<, should also be available for your type.

Arbitrary supplies three static functions:

  • generate which returns a single value according to a loose notion of "generation", allowing you to alter the "size" of the generated value

  • generate_n, which is similar, but with a stricter definition of size -- see Complexity below

  • shrink which takes a value, and returns a vector of values based on it. For types that don't make sense to shrink, shrink should return an empty vector. It should also return an empty vector if the argument has been shrunk enough.

Both generate and generate_n take an argument that will be used to seed an RNG. On failure, the failing seed will be reported so that you can reproduce the test.

If Testinator finds that a property fails to hold for a given value, it will call shrink in an attempt to find the smallest test case that breaks the property. For example, a test on a string that breaks if 'A' is present may produce:

Failed: ~+9Sbh~"D q`A%:-\_+G
Failed: q`A%:-\_+G
Failed: q`A%:
Failed: A%:
Failed: A
Reproduce failure with --seed=1419143051
FAIL: BrokenStringProperty

Examples of usage can be found in property.cpp.


Sometimes you want to time tests. You can set up a timed test easily, just like a regular test. There is no return value, because it's assumed the test exists so you can see what time it takes.

DEF_TIMED_TEST(TestName, SuiteName)
  // your logic here...

And you will see output like:

TestName: 100 tests run in 1206146ns (12061 ns per test).


Sometimes timing isn't enough, and what you really want to test is: what is the complexity of my algorithm? You might want to do this to get some kind of guarantee your algorithm will scale, for example. You can use an algorithmic complexity property, similar to a property, but with an extra "expected complexity" value (ORDER_1, ORDER_LOG_N, ORDER_N, ORDER_N_LOG_N, or ORDER_N2). Once again, there is no return value because the test exists only to measure complexity.

DEF_COMPLEXITY_PROPERTY(ThisIsOrderN, Complexity, ORDER_N, const string& s)
  max_element(s.begin(), s.end());

Generating values for use in complexity properties will call generate_n on the Arbitrary class.

When measuring complexity, timing is of course important. If the function is very small and optimized by the compiler, Testinator may not be able to accurately measure the time. Also, if the test function takes an argument by value (rather than by const ref) a copy will be incurred, which may typically push the complexity to O(n).

If the complexity test comes in at (or under) the expected complexity, it will be considered a pass.

Output Formatters

The default output formatter uses ANSI coloring (use --nocolor to turn it off) and normally omits output from passing tests (use --verbose to show the output of all tests).

An output formatter for the Test Anything Protocol is also available (use --output=TAP).

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