test: reorg #15698

Problem:
Subdirectories like "visual", "insert", "normal" encourage people to
separate *related* tests for no good reason.  Typically the _mode_ is
not the relevant topic of a test (and when it is, _then_ create
an appropriate describe() or it()).

Solution:
- Delete the various `test/functional/<mode>/` subdirectories, move
  their tests to more meaningful topics.
- Rename `…/normal/` to `…/editor/`.
  - Move or merge `…/visual/*` and `…/insert/*` tests into here where
    appropriate.
- Rename `…/eval/` to `…/vimscript/`.
  - Move `…/viml/*` into here also.

* test(reorg): insert/* => editor/mode_insert_spec.lua
* test(reorg): cmdline/* => editor/mode_cmdline_spec.lua
* test(reorg): eval core tests => eval_spec.lua

test/functional/vimscript/reltime_spec.lua

@@ -0,0 +1,53 @@
+local helpers = require('test.functional.helpers')(after_each)
+local clear, eq, ok = helpers.clear,  helpers.eq, helpers.ok
+local neq, command, funcs  = helpers.neq, helpers.command, helpers.funcs
+local reltime, reltimestr, reltimefloat = funcs.reltime, funcs.reltimestr, funcs.reltimefloat
+
+describe('reltimestr(), reltimefloat()', function()
+  before_each(clear)
+
+  it('acceptance', function()
+    local now = reltime()
+    command('sleep 10m')
+    local later = reltime()
+    local elapsed = reltime(now)
+
+    neq(reltimestr(elapsed), '0.0')
+    ok(reltimefloat(elapsed) > 0.0)
+    -- original vim test for < 0.1, but easily fails on travis
+    ok(nil ~= string.match(reltimestr(elapsed), "0%."))
+    ok(reltimefloat(elapsed) < 1.0)
+
+    local same = reltime(now, now)
+    local samestr = string.gsub(reltimestr(same), ' ', '')
+    samestr = string.sub(samestr, 1, 5)
+
+    eq('0.000', samestr)
+    eq(0.0, reltimefloat(same))
+
+    local differs = reltime(now, later)
+    neq(reltimestr(differs), '0.0')
+    ok(reltimefloat(differs) > 0.0)
+    -- original vim test for < 0.1, but easily fails on travis
+    ok(nil ~= string.match(reltimestr(differs), "0%."))
+    ok(reltimefloat(differs) < 1.0)
+  end)
+
+  it('(start - end) returns negative #10452', function()
+    local older_time = reltime()
+    command('sleep 1m')
+    local newer_time = reltime()
+
+    -- Start/end swapped: should be something like -0.002123.
+    local tm_s = tonumber(reltimestr(reltime(newer_time, older_time)))
+    local tm_f = reltimefloat(reltime(newer_time, older_time))
+    ok(tm_s < 0 and tm_s > -10)
+    ok(tm_f < 0 and tm_f > -10)
+
+    -- Not swapped: should be something like 0.002123.
+    tm_s = tonumber(reltimestr(reltime(older_time, newer_time)))
+    tm_f = reltimefloat(reltime(older_time, newer_time))
+    ok(tm_s > 0 and tm_s < 10)
+    ok(tm_f > 0 and tm_f < 10)
+  end)
+end)