1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
|
<a id="top"></a>
# Supplying main() yourself
**Contents**<br>
[Let Catch take full control of args and config](#let-catch-take-full-control-of-args-and-config)<br>
[Amending the config](#amending-the-config)<br>
[Adding your own command line options](#adding-your-own-command-line-options)<br>
[Version detection](#version-detection)<br>
The easiest way to use Catch is to let it supply ```main()``` for you and handle configuring itself from the command line.
This is achieved by writing ```#define CATCH_CONFIG_MAIN``` before the ```#include "catch.hpp"``` in *exactly one* source file.
Sometimes, though, you need to write your own version of main(). You can do this by writing ```#define CATCH_CONFIG_RUNNER``` instead. Now you are free to write ```main()``` as normal and call into Catch yourself manually.
You now have a lot of flexibility - but here are three recipes to get your started:
## Let Catch take full control of args and config
If you just need to have code that executes before and/ or after Catch this is the simplest option.
```c++
#define CATCH_CONFIG_RUNNER
#include "catch.hpp"
int main( int argc, char* argv[] ) {
// global setup...
int result = Catch::Session().run( argc, argv );
// global clean-up...
return result;
}
```
## Amending the config
If you still want Catch to process the command line, but you want to programmatically tweak the config, you can do so in one of two ways:
```c++
#define CATCH_CONFIG_RUNNER
#include "catch.hpp"
int main( int argc, char* argv[] )
{
Catch::Session session; // There must be exactly one instance
// writing to session.configData() here sets defaults
// this is the preferred way to set them
int returnCode = session.applyCommandLine( argc, argv );
if( returnCode != 0 ) // Indicates a command line error
return returnCode;
// writing to session.configData() or session.Config() here
// overrides command line args
// only do this if you know you need to
int numFailed = session.run();
// numFailed is clamped to 255 as some unices only use the lower 8 bits.
// This clamping has already been applied, so just return it here
// You can also do any post run clean-up here
return numFailed;
}
```
Take a look at the definitions of Config and ConfigData to see what you can do with them.
To take full control of the config simply omit the call to ```applyCommandLine()```.
## Adding your own command line options
Catch embeds a powerful command line parser called [Clara](https://github.com/philsquared/Clara).
As of Catch2 (and Clara 1.0) Clara allows you to write _composable_ option and argument parsers,
so extending Catch's own command line options is now easy.
```c++
#define CATCH_CONFIG_RUNNER
#include "catch.hpp"
int main( int argc, char* argv[] )
{
Catch::Session session; // There must be exactly one instance
int height = 0; // Some user variable you want to be able to set
// Build a new parser on top of Catch's
using namespace Catch::clara;
auto cli
= session.cli() // Get Catch's composite command line parser
| Opt( height, "height" ) // bind variable to a new option, with a hint string
["-g"]["--height"] // the option names it will respond to
("how high?"); // description string for the help output
// Now pass the new composite back to Catch so it uses that
session.cli( cli );
// Let Catch (using Clara) parse the command line
int returnCode = session.applyCommandLine( argc, argv );
if( returnCode != 0 ) // Indicates a command line error
return returnCode;
// if set on the command line then 'height' is now set at this point
if( height > 0 )
std::cout << "height: " << height << std::endl;
return session.run();
}
```
See the [Clara documentation](https://github.com/philsquared/Clara/blob/master/README.md) for more details.
## Version detection
Catch provides a triplet of macros providing the header's version,
* `CATCH_VERSION_MAJOR`
* `CATCH_VERSION_MINOR`
* `CATCH_VERSION_PATCH`
these macros expand into a single number, that corresponds to the appropriate
part of the version. As an example, given single header version v2.3.4,
the macros would expand into `2`, `3`, and `4` respectively.
---
[Home](Readme.md#top)
|
