legacy tests: migrate test35. #1318

Migrate vim's integration test 35 (increment/decrement commands) to
lua/busted.

src/nvim/testdir/test35.in

@@ -1,21 +0,0 @@
-Test Ctrl-A and Ctrl-X, which increment and decrement decimal, hexadecimal,
-and octal numbers.
-
-STARTTEST
-/^start-here
-:set nrformats=octal,hex
-j
102
ll
64
128$
-:set nrformats=octal
-0
102
l2
w65
129blx6lD
-:set nrformats=hex
-0101l257
Txldt 
  
-:set nrformats=
-0200l100w78
k
-:$-3,$wq! test.out
-ENDTEST
-
-start-here
-100     0x100     077     0
-100     0x100     077     
-100     0x100     077     0xfF     0xFf
-100     0x100     077     

src/nvim/testdir/test35.ok

@@ -1,4 +0,0 @@
-0     0x0ff     0000     -1
-0     1x100     0777777
--1     0x0     078     0xFE     0xfe
--100     -100x100     000     

test/functional/legacy/035_increment_and_decrement_spec.lua

@@ -0,0 +1,44 @@
+-- Test Ctrl-A and Ctrl-X, which increment and decrement decimal, hexadecimal,
+-- and octal numbers.
+
+local helpers = require('test.functional.helpers')
+local clear, feed, insert = helpers.clear, helpers.feed, helpers.insert
+local execute, expect = helpers.execute, helpers.expect
+
+describe('increment and decrement commands', function()
+  setup(clear)
+
+  it('should work', function()
+    -- Insert some numbers in various bases.
+    insert([[
+      100     0x100     077     0
+      100     0x100     077
+      100     0x100     077     0xfF     0xFf
+      100     0x100     077]])
+
+    -- Increment and decrement numbers in the first row, interpreting the
+    -- numbers as decimal, octal or hexadecimal.
+    execute('set nrformats=octal,hex', '1')
+    feed('
102
ll
64
128$')
+
+    -- For the second row, treat the numbers as decimal or octal.
+    -- 0x100 should be interpreted as decimal 0, the character x, and decimal 100.
+    execute('set nrformats=octal', '2')
+    feed('0
102
l2
w65
129blx6lD')
+
+    -- For the third row, treat the numbers as decimal or hexadecimal.
+    -- 077 should be interpreted as decimal 77.
+    execute('set nrformats=hex', '3')
+    feed('0101l257
Txldt 
  ')
+
+    -- For the last row, interpret all numbers as decimal.
+    execute('set nrformats=', '4')
+    feed('0200l100w78
')
+
+    expect([[
+      0     0x0ff     0000     -1
+      0     1x100     0777777
+      -1     0x0     078     0xFE     0xfe
+      -100     -100x100     000]])
+  end)
+end)