modules: Add an unstable-rust module

Like other language specific modules this module is module for holding
rust specific helpers. This commit adds a test() function, which
simplifies using rust's internal unittest mechanism.

Rust tests are generally placed in the same code files as they are
testing, in contrast to languages like C/C++ and python which generally
place the tests in separate translation units. For meson this is
somewhat problematic from a repetition point of view, as the only
changes are generally adding --test, and possibly some dependencies.

The rustmod.test() method provides a mechanism to remove the repatition:
it takes a rust target, copies it, and then addes the `--test` option,
then creates a Test() target with the `rust` protocol. You can pass
additional dependencies via the `dependencies` keyword. This all makes
for a nice, DRY, test definition.

1 files changed, 1 insertions, 0 deletions

diff --git a/docs/markdown/_Sidebar.md b/docs/markdown/_Sidebar.md
index 2637d686d..0ca1762b5 100644
--- a/docs/markdown/_Sidebar.md
+++ b/docs/markdown/_Sidebar.md
@@ -12,3 +12,4 @@
 * [gnome](Gnome-module.md)
 * [i18n](i18n-module.md)
 * [pkgconfig](Pkgconfig-module.md)
+* [rust](Rust-module.md)