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@ -22,7 +22,7 @@ But functions and methods can also be written inline in header files. The downsi
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Because Catch is implemented *entirely* in headers you might think that the whole of Catch must be compiled into every translation unit that uses it! Actually it's not quite as bad as that. Catch mitigates this situation by effectively maintaining the traditional separation between the implementation code and declarations. Internally the implementation code is protected by ```#ifdef```s and is conditionally compiled into only one translation unit. This translation unit is that one that ```#define```s ```CATCH_CONFIG_MAIN``` or ```CATCH_CONFIG_RUNNER```. Let's call this the main source file.
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As a result the main source file *does* compile the whole of Catch every time! So it makes sense to dedicate this file to *only* ```#define```-ing the identifier and ```#include```-ing Catch (and implementing the runner code, if you're doing that). Keep all your test cases in other files. This way you won't pay the recompilation cost for the whole of Catch
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As a result the main source file *does* compile the whole of Catch every time! So it makes sense to dedicate this file to *only* ```#define```-ing the identifier and ```#include```-ing Catch (and implementing the runner code, if you're doing that). Keep all your test cases in other files. This way you won't pay the recompilation cost for the whole of Catch.
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## Practical example
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Assume you have the `Factorial` function from the [tutorial](tutorial.md#top) in `factorial.cpp` (with forward declaration in `factorial.h`) and want to test it and keep the compile times down when adding new tests. Then you should have 2 files, `tests-main.cpp` and `tests-factorial.cpp`:
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@ -106,7 +106,7 @@ Of course there are still more issues to deal with. For example we'll hit proble
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Although this was a simple test it's been enough to demonstrate a few things about how Catch is used. Let's take a moment to consider those before we move on.
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1. All we did was ```#define``` one identifier and ```#include``` one header and we got everything - even an implementation of ```main()``` that will [respond to command line arguments](command-line.md#top). You can only use that ```#define``` in one implementation file, for (hopefully) obvious reasons. Once you have more than one file with unit tests in you'll just ```#include "catch.hpp"``` and go. Usually it's a good idea to have a dedicated implementation file that just has ```#define CATCH_CONFIG_MAIN``` and ```#include "catch.hpp"```. You can also provide your own implementation of main and drive Catch yourself (see [Supplying-your-own-main()](own-main.md#top)).
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2. We introduce test cases with the ```TEST_CASE``` macro. This macro takes one or two arguments - a free form test name and, optionally, one or more tags (for more see <a href="#test-cases-and-sections">Test cases and Sections</a>, ). The test name must be unique. You can run sets of tests by specifying a wildcarded test name or a tag expression. See the [command line docs](command-line.md#top) for more information on running tests.
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2. We introduce test cases with the ```TEST_CASE``` macro. This macro takes one or two arguments - a free form test name and, optionally, one or more tags (for more see <a href="#test-cases-and-sections">Test cases and Sections</a>). The test name must be unique. You can run sets of tests by specifying a wildcarded test name or a tag expression. See the [command line docs](command-line.md#top) for more information on running tests.
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3. The name and tags arguments are just strings. We haven't had to declare a function or method - or explicitly register the test case anywhere. Behind the scenes a function with a generated name is defined for you, and automatically registered using static registry classes. By abstracting the function name away we can name our tests without the constraints of identifier names.
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4. We write our individual test assertions using the ```REQUIRE``` macro. Rather than a separate macro for each type of condition we express the condition naturally using C/C++ syntax. Behind the scenes a simple set of expression templates captures the left-hand-side and right-hand-side of the expression so we can display the values in our test report. As we'll see later there _are_ other assertion macros - but because of this technique the number of them is drastically reduced.
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