refactor(tests): introduce testprg()

Also:
- Add a describe('shell :!') section to system_spec.
- Make the test for #16271 work on systems without powershell.

test/functional/vimscript/system_spec.lua

@@ -1,7 +1,7 @@
 local helpers = require('test.functional.helpers')(after_each)
 
 local assert_alive = helpers.assert_alive
-local nvim_dir = helpers.nvim_dir
+local testprg = helpers.testprg
 local eq, call, clear, eval, feed_command, feed, nvim =
   helpers.eq, helpers.call, helpers.clear, helpers.eval, helpers.feed_command,
   helpers.feed, helpers.nvim
@@ -32,10 +32,6 @@ describe('system()', function()
   before_each(clear)
 
   describe('command passed as a List', function()
-    local function printargs_path()
-      return nvim_dir..'/printargs-test' .. (iswin() and '.exe' or '')
-    end
-
     it('throws error if cmd[0] is not executable', function()
       eq("Vim:E475: Invalid value for argument cmd: 'this-should-not-exist' is not executable",
         pcall_err(call, 'system', { 'this-should-not-exist' }))
@@ -68,16 +64,16 @@ describe('system()', function()
 
     it('quotes arguments correctly #5280', function()
       local out = call('system',
-        { printargs_path(), [[1]], [[2 "3]], [[4 ' 5]], [[6 ' 7']] })
+        { testprg('printargs-test'), [[1]], [[2 "3]], [[4 ' 5]], [[6 ' 7']] })
 
       eq(0, eval('v:shell_error'))
       eq([[arg1=1;arg2=2 "3;arg3=4 ' 5;arg4=6 ' 7';]], out)
 
-      out = call('system', { printargs_path(), [['1]], [[2 "3]] })
+      out = call('system', { testprg('printargs-test'), [['1]], [[2 "3]] })
       eq(0, eval('v:shell_error'))
       eq([[arg1='1;arg2=2 "3;]], out)
 
-      out = call('system', { printargs_path(), "A\nB" })
+      out = call('system', { testprg('printargs-test'), "A\nB" })
       eq(0, eval('v:shell_error'))
       eq("arg1=A\nB;", out)
     end)
@@ -169,7 +165,7 @@ describe('system()', function()
         end
       end)
 
-      it('works with powershell', function()
+      it('with powershell', function()
         helpers.set_shell_powershell()
         eq('a\nb\n', eval([[system('Write-Output a b')]]))
         eq('C:\\\n', eval([[system('cd c:\; (Get-Location).Path')]]))
@@ -177,12 +173,11 @@ describe('system()', function()
       end)
     end
 
-    it('works with powershell w/ UTF-8 text (#13713)', function()
+    it('powershell w/ UTF-8 text #13713', function()
       if not helpers.has_powershell() then
         pending("not tested; powershell was not found", function() end)
         return
       end
-      -- Should work with recommended config used in helper
       helpers.set_shell_powershell()
       eq('ああ\n', eval([[system('Write-Output "ああ"')]]))
       -- Sanity test w/ default encoding
@@ -432,7 +427,7 @@ describe('system()', function()
   end)
 
   it("with a program that doesn't close stdout will exit properly after passing input", function()
-    local out = eval(string.format("system('%s', 'clip-data')", nvim_dir..'/streams-test'))
+    local out = eval(string.format("system('%s', 'clip-data')", testprg('streams-test')))
     assert(out:sub(0, 5) == 'pid: ', out)
     os_kill(out:match("%d+"))
   end)
@@ -611,17 +606,16 @@ describe('systemlist()', function()
   end)
 
   it("with a program that doesn't close stdout will exit properly after passing input", function()
-    local out = eval(string.format("systemlist('%s', 'clip-data')", nvim_dir..'/streams-test'))
+    local out = eval(string.format("systemlist('%s', 'clip-data')", testprg('streams-test')))
     assert(out[1]:sub(0, 5) == 'pid: ', out)
     os_kill(out[1]:match("%d+"))
   end)
 
-  it('works with powershell w/ UTF-8 text (#13713)', function()
+  it('powershell w/ UTF-8 text #13713', function()
     if not helpers.has_powershell() then
       pending("not tested; powershell was not found", function() end)
       return
     end
-    -- Should work with recommended config used in helper
     helpers.set_shell_powershell()
     eq({iswin() and 'あ\r' or 'あ'}, eval([[systemlist('Write-Output あ')]]))
     -- Sanity test w/ default encoding
@@ -633,28 +627,30 @@ describe('systemlist()', function()
 
 end)
 
-it(':{range}! works with powershell for filter and redirection #16271', function()
-  clear()
-  if not helpers.has_powershell() then
-    pending("not tested; powershell was not found", function() end)
-    return
-  end
-  local screen = Screen.new(500, 8)
-  screen:attach()
-  helpers.set_shell_powershell()
-  insert([[
-    3
-    1
-    4
-    2]])
-  feed(':4verbose %!sort<cr>')
-  screen:expect{
-    any=[[Executing command: "Start%-Process sort %-RedirectStandardInput .* %-RedirectStandardOutput .* %-NoNewWindow %-Wait".*4 lines filtered.*Press ENTER or type command to continue]]
-  }
-  feed('<CR>')
-  expect([[
-    1
-    2
-    3
-    4]])
+describe('shell :!', function()
+  before_each(clear)
+
+  it(':{range}! with powershell filter/redirect #16271', function()
+    local screen = Screen.new(500, 8)
+    screen:attach()
+    local found = helpers.set_shell_powershell(true)
+    insert([[
+      3
+      1
+      4
+      2]])
+    feed(':4verbose %!sort<cr>')
+    screen:expect{
+      any=[[Executing command: .?Start%-Process sort %-RedirectStandardInput .* %-RedirectStandardOutput .* %-NoNewWindow %-Wait]]
+    }
+    feed('<CR>')
+    if found then
+      -- Not using fake powershell, so we can test the result.
+      expect([[
+        1
+        2
+        3
+        4]])
+    end
+  end)
 end)