test: add compiler tests

test/github-theme/config/compiler_spec.lua

@@ -0,0 +1,25 @@
+local assert = require('luassert')
+local t_util = require('github-theme._test.util')
+local uniqgrp = t_util.unique_hlgroup
+
+if vim.fn.has('nvim-0.9.0') == 0 or vim.fn.has('nvim-0.9.0') == false then
+  return
+end
+
+describe('compiler', function()
+  it('should consider previously-set overrides (1)', function()
+    local same_opts = {}
+    require('github-theme').setup(same_opts)
+    require('github-theme.override').groups = { all = { Normal = { link = uniqgrp } } }
+    require('github-theme').setup(same_opts)
+    vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
+    assert.same({ link = uniqgrp }, t_util.get_hl('Normal', true))
+  end)
+
+  it('should consider previously-set overrides (2)', function()
+    require('github-theme').setup({})
+    require('github-theme.override').groups = { all = { Normal = { link = uniqgrp } } }
+    vim.cmd.colorscheme({ args = { 'github_dark_dimmed' } })
+    assert.same({ link = uniqgrp }, t_util.get_hl('Normal', true))
+  end)
+end)