While Catch fully supports the traditional, *x*Unit, style of class-based fixtures containing test case methods this is not the preferred style.
Instead Catch provides a powerful mechanism for nesting test case sections within a test case. For a more detailed discussion see the [tutorial](tutorial.md#testCasesAndSections).
Test cases and sections are very easy to use in practice:
**TEST_CASE(** _test name_ [**,** _tags_ ] **)**
**SECTION(** _section name_**)**
_test name_ and _section name_ are free form, quoted, strings. The optional _tags_ argument is a quoted string containing one or more tags enclosed in square brackets. Tags are discussed below. Test names must be unique within the Catch executable.
In addition to Catch's take on the classic style of test cases, Catch supports an alternative syntax that allow tests to be written as "executable specifications" (one of the early goals of [BDD](http://dannorth.net/introducing-bdd/)). This set of macros map on to ```TEST_CASE```s and ```SECTION```s, with a little internal support to make them smoother to work with.
This macro maps onto ```TEST_CASE``` and works in the same way, except that the test case name will be prefixed by "Scenario: "
**GIVEN(** _something_**)**
**WHEN(** _something_**)**
**THEN(** _something_**)**
These macros map onto ```SECTION```s except that the section names are the _something_s prefixed by "given: ", "when: " or "then: " respectively.
**AND_WHEN(** _something_**)**
**AND_THEN(** _something_**)**
Similar to ```WHEN``` and ```THEN``` except that the prefixes start with "and ". These are used to chain ```WHEN```s and ```THEN```s together.
When any of these macros are used the console reporter recognises them and formats the test case header such that the Givens, Whens and Thens are aligned to aid readability.
Other than the additional prefixes and the formatting in the console reporter these macros behave exactly as ```TEST_CASE```s and ```SECTION```s. As such there is nothing enforcing the correct sequencing of these macros - that's up to the programmer!
