test(impl): add test

spec/fixtures/impl/impl_input.go

@@ -0,0 +1,3 @@
+package main
+
+type Tester struct{}

spec/fixtures/impl/impl_output.go

@@ -0,0 +1,8 @@
+package main
+
+type Tester2 struct{}
+
+func (w *Tester2) Write(p []byte) (n int, err error) {
+	panic("not implemented") // TODO: Implement
+}
+

spec/integration/impl_test.lua

@@ -10,5 +10,19 @@ local T = MiniTest.new_set {
   },
 }
 T["impl"] = MiniTest.new_set {}
+T["impl"]["works"] = function()
+  local tmp = t.tmpfile()
+  local fixtures = t.fixtures.read "impl/impl"
+  t.fixtures.write(tmp, fixtures.input)
+
+  child.cmd("silent edit " .. tmp)
+  child.fn.setpos(".", { child.fn.bufnr "%", 3, 6, 0 })
+  child.cmd "GoImpl w io.Writer"
+  child.cmd "write"
+
+  -- since "impl" won't implement interface if it's already implemented i went with this hack
+  local rhs = fixtures.output:gsub("Tester2", "Tester")
+  t.eq(t.readfile(tmp), rhs)
+end
 
 return T