1 // (C) Copyright 2015 Boost.Test team.
2 // Distributed under the Boost Software License, Version 1.0.
3 // (See accompanying file LICENSE_1_0.txt or copy at
4 // http://www.boost.org/LICENSE_1_0.txt)
5
6 // See http://www.boost.org/libs/test for the library home page.
7
8 //[example_code
9 #define BOOST_TEST_MODULE example
10 #include <boost/test/included/unit_test.hpp>
11 #include <stdexcept>
12 #include <fstream>
13
14 //! Computes the histogram of the words in a text file
15 class FileWordHistogram
16 {
17 public:
18 //!@throw std::exception if the file does not exist
FileWordHistogram(std::string filename)19 FileWordHistogram(std::string filename) : is_processed(false), fileStream_(filename) {
20 if(!fileStream_.is_open()) throw std::runtime_error("Cannot open the file");
21 }
22
23 //! @returns true on success, false otherwise
process()24 bool process() {
25 if(is_processed) return true;
26
27 // ...
28 is_processed = true;
29 return true;
30 }
31
32 //!@pre process has been called with status success
33 //!@throw std::logic_error if preconditions not met
34 std::map<std::string, std::size_t>
result() const35 result() const {
36 if(!is_processed)
37 throw std::runtime_error("\"process\" has not been called or was not successful");
38 return histogram;
39 }
40
41 private:
42 bool is_processed;
43 std::ifstream fileStream_;
44 std::map<std::string, std::size_t> histogram;
45 };
46
BOOST_AUTO_TEST_CASE(test_throw_behaviour)47 BOOST_AUTO_TEST_CASE( test_throw_behaviour )
48 {
49 // __FILE__ is accessible, no exception expected
50 BOOST_REQUIRE_NO_THROW( FileWordHistogram(__FILE__) );
51
52 // ".. __FILE__" does not exist, API says std::exception, and implementation
53 // raises std::runtime_error child of std::exception
54 BOOST_CHECK_THROW( FileWordHistogram(".." __FILE__), std::exception );
55
56 {
57 FileWordHistogram instance(__FILE__);
58
59 // api says "std::logic_error", implementation is wrong.
60 // std::runtime_error not a child of std::logic_error, not intercepted
61 // here.
62 BOOST_CHECK_THROW(instance.result(), std::logic_error);
63 }
64 }
65 //]
66