Enable test layer configuration (#2669)

* Enable test layer configuration

* test layer settings separator changed from - to _

autoload/SpaceVim/layers/test.vim

@@ -39,3 +39,13 @@ function! SpaceVim#layers#test#config() abort
   let g:test#custom_strategies = {'spacevim': function('SpaceVim#plugins#runner#open')}
   let g:test#strategy = 'spacevim'
 endfunction
+
+function! SpaceVim#layers#test#set_variable(var) abort
+  let l:override = get(a:var, 'override_config', {})
+  if !empty(l:override)
+    for l:option in keys(l:override)
+      let l:varname = 'test#'.substitute(l:option, '_', '#', 'g')
+      execute 'let g:'.l:varname.' = '."'".l:override[l:option]."'"
+    endfor
+  endif
+endfunction

docs/layers/test.md

@@ -26,6 +26,27 @@ To use this configuration layer, add following snippet to your custom configurat
   name = "test"
 ```
 
+## Configuration
+
+To set or override any configuration ([see supported settings here](https://github.com/janko/vim-test)) you may use the `override_config`:
+
+```toml
+[[layers]]
+  name = "test"
+  [layers.override_config]
+    java_runner = "gradletest"
+    java_gradletest_executable = "./gradlew test"
+```
+
+In the example above is equivalent to adding the following in viml:
+
+```viml
+let test#java#runner = "gradletest"
+let test#java#gradletest#executable = "./gradlew test"
+```
+
+In essence, it replaces `_` with `#` and prepends `test#` to the keys inside `override_config`.
+
 ## Key bindings
 
 | Key Binding | Description                                                                                                                                                                                                                                                                             |