add Previm and window management

sources_non_forked/previm/test/plugin/previm_test.vim

@@ -0,0 +1,46 @@
+let s:t = themis#suite('valid filetype for using :PrevimOpen')
+let s:assert = themis#helper('assert')
+
+function! s:t.before()
+  let self._ft = &filetype
+endfunction
+
+function! s:t.after()
+  let &filetype = self._ft
+  call s:_clean_command()
+endfunction
+
+function! s:_clean_command()
+  if exists(':PrevimOpen') == 2
+    delcommand PrevimOpen
+  endif
+endfunction
+
+" helper
+function! s:_assert_filetype(ft, expected)
+  let &filetype = a:ft
+  let actual = exists(':PrevimOpen')
+  if actual !=# a:expected
+    call s:assert.fail(printf("'%s': expected %d but actual %d", a:ft, a:expected, actual))
+  endif
+endfunction
+"""
+
+function! s:t.invalid_filetype()
+  let not_exist_command = 0
+  for type in ['', 'rb', 'php']
+    call s:_assert_filetype(type, not_exist_command)
+  endfor
+endfunction
+
+function! s:t.valid_filetype()
+  let exist_command = 2
+  for type in [
+        \ 'markdown', 'mkd', 'rst', 'textile',
+        \ 'aaa.markdown', 'mkd.foo', 'bb.rst.cc', 'a.b.c.textile',
+        \]
+    call s:_assert_filetype(type, exist_command)
+    call s:_clean_command()
+  endfor
+endfunction
+