Header only C++14 mocking framework
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trompe l'oeil noun (Concise Encyclopedia)
Style of representation in which a painted object is intended to deceive the viewer into believing it is the object itself...

What is it?

A thread-safe header-only mocking framework for C++11/14 using the Boost Software License 1.0


Also, follow up with the post on sequencing for examples on how to restrict or relax allowed sequences of matching calls.

If you want to contribute, read ACCU overload 125 to learn the internals.


#include <trompeloeil.hpp>

class Interface
  virtual ~Interface() = default;
  virtual bool foo(int, std::string& s) = 0;
  virtual bool bar(int) = 0;
  virtual bool bar(std::string) = 0;

void interface_func(Interface*); // function to test

class Mock : public Interface
  MAKE_MOCK2(foo, bool(int, std::string&),override);
  MAKE_MOCK1(bar, bool(int),override);
  MAKE_MOCK1(bar, bool(std::string),override);
  MAKE_MOCK0(baz, void()); // not from Interface

  using trompeloeil::_;  // wild card for matching any value
  using trompeloeil::gt; // greater-than match

  Mock m;

  trompeloeil::sequence seq1, seq2;  // control order of matching calls

  int local_var = 0;

  REQUIRE_CALL(m, bar(ANY(int)))     // expect call to m.bar(int)
    .LR_SIDE_EFFECT(local_var = _1)  // set captured variable to value of param
    .RETURN(_1 > 0)                  // return value depending on param value
    .IN_SEQUENCE(seq1)               // must be first match for seq1
    .TIMES(AT_LEAST(1));             // can be called several times

  FORBID_CALL(m, bar(0));            // but m.bar(0) is not allowed

  REQUIRE_CALL(m, bar("word"))       // expect one call to m.bar(std::string)
    .IN_SEQUENCE(seq2);              // must be first match for seq2

  REQUIRE_CALL(m, foo(gt(2), _))     // expect call to foo(int,std::string&)
    .WITH(_2 == "")                  // with int > 2 and empty string
    .IN_SEQUENCE(seq1, seq2)         // last for both seq1 and seq2
    .SIDE_EFFECT(_2 = "cat")         // and set param string to "cat"


  // all the above expectations must be fulfilled here

Compiler compatibility

Trompeloeil is known to work with:

  • GCC 4.8.4+, 4.9.3+, 5, 6, 7, 8
  • Clang 3.5, 3.6, 3.7, 3.8, 3.9, 4, 5, 6
  • Visual Studio 2015, 2017

Latest patch level releases are assumed in the versions listed above.

Further details on C++11 support, platform and library limitations, may be found in