test: Add some specs for the viml function system()

These new specs replace src/nvim/testdir/test_system

src/nvim/testdir/Makefile

@@ -35,8 +35,7 @@ SCRIPTS := test_autoformat_join.out                                    \
            test_listlbr.out test_listlbr_utf8.out                      \
            test_changelist.out                                         \
            test_breakindent.out                                        \
-           test_insertcount.out                                        \
+           test_insertcount.out
-           test_systen.in
 
 SCRIPTS_GUI := test16.out
 

src/nvim/testdir/test_system.ok

@@ -1,3 +0,0 @@
-
-ab
cd
-['ab
cd']

test/functional/shell/viml_system_spec.lua

@@ -0,0 +1,125 @@
+-- Specs for
+-- - `system()`
+-- - `systemlist()`
+
+local helpers = require('test.functional.helpers')
+local eq, clear, eval, feed =
+  helpers.eq, helpers.clear, helpers.eval, helpers.feed
+
+
+local function create_file_with_nuls(name)
+  return function()
+    feed('ipart1<C-V>000part2<C-V>000part3<ESC>:w '..name..'<CR>')
+  end
+end
+
+local function delete_file(name)
+  return function()
+    eval("delete('"..name.."')")
+  end
+end
+
+
+describe('system()', function()
+  before_each(clear)
+
+  describe('passing no input', function()
+    it('returns the program output', function()
+      eq("echoed", eval('system("echo -n echoed")'))
+    end)
+  end)
+
+  describe('passing input', function()
+    it('returns the program output', function()
+      eq("input", eval('system("cat -", "input")'))
+    end)
+  end)
+
+  describe('passing number as input', function()
+    it('stringifies the input', function()
+      eq('1', eval('system("cat", 1)'))
+    end)
+  end)
+
+  describe('with output containing NULs', function()
+    local fname = 'Xtest'
+
+    setup(create_file_with_nuls(fname))
+    teardown(delete_file(fname))
+
+    it('replaces NULs by SOH characters', function()
+      eq('part1\001part2\001part3\n', eval('system("cat '..fname..'")'))
+    end)
+  end)
+
+  describe('passing list as input', function()
+    it('joins list items with linefeed characters', function()
+      eq('line1\nline2\nline3',
+        eval("system('cat -', ['line1', 'line2', 'line3'])"))
+    end)
+
+    -- Notice that NULs are converted to SOH when the data is read back. This
+    -- is inconsistent and is a good reason for the existence of the
+    -- `systemlist()` function, where input and output map to the same
+    -- characters(see the following tests with `systemlist()` below)
+    describe('with linefeed characters inside list items', function()
+      it('converts linefeed characters to NULs', function()
+        eq('l1\001p2\nline2\001a\001b\nl3',
+          eval([[system('cat -', ["l1\np2", "line2\na\nb", 'l3'])]]))
+      end)
+    end)
+
+    describe('with leading/trailing whitespace characters on items', function()
+      it('preserves whitespace, replacing linefeeds by NULs', function()
+        eq('line \nline2\001\n\001line3',
+          eval([[system('cat -', ['line ', "line2\n", "\nline3"])]]))
+      end)
+    end)
+  end)
+end)
+
+describe('systemlist()', function()
+  -- behavior is similar to `system()` but it returns a list instead of a
+  -- string.
+  before_each(clear)
+
+  describe('passing string with linefeed characters as input', function()
+    it('splits the output on linefeed characters', function()
+      eq({'abc', 'def', 'ghi'}, eval([[systemlist("cat -", "abc\ndef\nghi")]]))
+    end)
+  end)
+
+  describe('with output containing NULs', function()
+    local fname = 'Xtest'
+
+    setup(create_file_with_nuls(fname))
+    teardown(delete_file(fname))
+
+    it('replaces NULs by newline characters', function()
+      eq({'part1\npart2\npart3'}, eval('systemlist("cat '..fname..'")'))
+    end)
+  end)
+
+  describe('passing list as input', function()
+    it('joins list items with linefeed characters', function()
+      eq({'line1', 'line2', 'line3'},
+        eval("systemlist('cat -', ['line1', 'line2', 'line3'])"))
+    end)
+
+    -- Unlike `system()` which uses SOH to represent NULs, with `systemlist()`
+    -- input and ouput are the same
+    describe('with linefeed characters inside list items', function()
+      it('converts linefeed characters to NULs', function()
+        eq({'l1\np2', 'line2\na\nb', 'l3'},
+          eval([[systemlist('cat -', ["l1\np2", "line2\na\nb", 'l3'])]]))
+      end)
+    end)
+
+    describe('with leading/trailing whitespace characters on items', function()
+      it('preserves whitespace, replacing linefeeds by NULs', function()
+        eq({'line ', 'line2\n', '\nline3'},
+          eval([[systemlist('cat -', ['line ', "line2\n", "\nline3"])]]))
+      end)
+    end)
+  end)
+end)