tests: improve testing (#80)

* chore: setup mini.test

* chore(ci): setup new test runner, install plugin deps

* chore(ci): test only on stable and nightly releases

* test: iferr

* test: struct_tags

* test: impl

* test: gotests

spec/integration/impl_test.lua

@@ -0,0 +1,55 @@
+local t = require "spec.testutils"
+
+local child = MiniTest.new_child_neovim()
+local T = MiniTest.new_set {
+  hooks = {
+    post_once = child.stop,
+    pre_case = function()
+      child.restart { "-u", t.mininit_path }
+    end,
+  },
+}
+T["impl"] = MiniTest.new_set {}
+T["impl"]["works w io.Writer"] = function()
+  local tmp = t.tmpfile()
+  local fixtures = t.get_fixtures "impl/writer"
+  t.writefile(tmp, fixtures.input)
+
+  child.cmd("silent edit " .. tmp)
+  child.fn.setpos(".", { child.fn.bufnr(tmp), 3, 6 })
+  child.cmd "GoImpl w io.Writer"
+  child.cmd "write"
+
+  -- NOTE: since "impl" won't implement interface if it's already implemented i went with this hack
+  local rhs = fixtures.output:gsub("Test2", "Test")
+  t.eq(t.readfile(tmp), rhs)
+end
+
+T["impl"]["works r Read io.Reader"] = function()
+  local tmp = t.tmpfile()
+  local fixtures = t.get_fixtures "impl/reader"
+  t.writefile(tmp, fixtures.input)
+
+  child.cmd("silent edit " .. tmp)
+  child.cmd "GoImpl r Read io.Reader"
+  child.cmd "write"
+
+  local rhs = fixtures.output:gsub("Read2", "Read")
+  t.eq(t.readfile(tmp), rhs)
+end
+
+T["impl"]["works io.Closer"] = function()
+  local tmp = t.tmpfile()
+  local fixtures = t.get_fixtures "impl/closer"
+  t.writefile(tmp, fixtures.input)
+
+  child.cmd("silent edit " .. tmp)
+  child.fn.setpos(".", { child.fn.bufnr(tmp), 3, 6 })
+  child.cmd "GoImpl io.Closer"
+  child.cmd "write"
+
+  local rhs = fixtures.output:gsub("Test2", "Test")
+  t.eq(t.readfile(tmp), rhs)
+end
+
+return T