Fix failing tests

plugin/airline.vim

@@ -81,6 +81,7 @@ function! s:airline_toggle()
     if exists("s:stl")
       let &stl = s:stl
     endif
+    call airline#highlighter#reset_hlcache()
 
     silent doautocmd User AirlineToggledOff
   else

t/builder.vim

@@ -19,6 +19,7 @@ describe 'active builder'
   end
 
   it 'should reuse highlight group if background colors match'
+    call airline#highlighter#reset_hlcache()
     highlight Foo1 ctermfg=1 ctermbg=2
     highlight Foo2 ctermfg=1 ctermbg=2
     call s:builder.add_section('Foo1', 'hello')
@@ -28,6 +29,7 @@ describe 'active builder'
   end
 
   it 'should switch highlight groups if foreground colors differ'
+    call airline#highlighter#reset_hlcache()
     highlight Foo1 ctermfg=1 ctermbg=2
     highlight Foo2 ctermfg=2 ctermbg=2
     call s:builder.add_section('Foo1', 'hello')

t/themes.vim

@@ -5,6 +5,7 @@ describe 'themes'
   end
 
   it 'should extract correct colors'
+    call airline#highlighter#reset_hlcache()
     highlight Foo ctermfg=1 ctermbg=2
     let colors = airline#themes#get_highlight('Foo')
     Expect colors[2] == '1'
@@ -12,6 +13,7 @@ describe 'themes'
   end
 
   it 'should extract from normal if colors unavailable'
+    call airline#highlighter#reset_hlcache()
     highlight Normal ctermfg=100 ctermbg=200
     highlight Foo ctermbg=2
     let colors = airline#themes#get_highlight('Foo')
@@ -20,6 +22,7 @@ describe 'themes'
   end
 
   it 'should flip target group if it is reversed'
+    call airline#highlighter#reset_hlcache()
     highlight Foo ctermbg=222 ctermfg=103 term=reverse
     let colors = airline#themes#get_highlight('Foo')
     Expect colors[2] == '222'
@@ -27,6 +30,8 @@ describe 'themes'
   end
 
   it 'should pass args through correctly'
+    call airline#highlighter#reset_hlcache()
+    hi clear Normal
     let hl = airline#themes#get_highlight('Foo', 'bold', 'italic')
     Expect hl == ['', '', 'NONE', 'NONE', 'bold,italic']