diff --git a/spec/fixtures/impl/closer_input.go b/spec/fixtures/impl/closer_input.go
new file mode 100644
index 0000000..e4d5f52
--- /dev/null
+++ b/spec/fixtures/impl/closer_input.go
@@ -0,0 +1,3 @@
+package main
+
+type CloserTest struct{}
diff --git a/spec/fixtures/impl/closer_output.go b/spec/fixtures/impl/closer_output.go
new file mode 100644
index 0000000..5e976f3
--- /dev/null
+++ b/spec/fixtures/impl/closer_output.go
@@ -0,0 +1,8 @@
+package main
+
+type CloserTest2 struct{}
+
+func (closertest *CloserTest2) Close() error {
+	panic("not implemented") // TODO: Implement
+}
+
diff --git a/spec/fixtures/impl/impl_input.go b/spec/fixtures/impl/impl_input.go
deleted file mode 100644
index 0310f84..0000000
--- a/spec/fixtures/impl/impl_input.go
+++ /dev/null
@@ -1,3 +0,0 @@
-package main
-
-type Tester struct{}
diff --git a/spec/fixtures/impl/impl_output.go b/spec/fixtures/impl/impl_output.go
deleted file mode 100644
index 26673a5..0000000
--- a/spec/fixtures/impl/impl_output.go
+++ /dev/null
@@ -1,8 +0,0 @@
-package main
-
-type Tester2 struct{}
-
-func (w *Tester2) Write(p []byte) (n int, err error) {
-	panic("not implemented") // TODO: Implement
-}
-
diff --git a/spec/fixtures/impl/reader_input.go b/spec/fixtures/impl/reader_input.go
new file mode 100644
index 0000000..ebc8eff
--- /dev/null
+++ b/spec/fixtures/impl/reader_input.go
@@ -0,0 +1,3 @@
+package main
+
+type Read struct{}
diff --git a/spec/fixtures/impl/reader_output.go b/spec/fixtures/impl/reader_output.go
new file mode 100644
index 0000000..26df873
--- /dev/null
+++ b/spec/fixtures/impl/reader_output.go
@@ -0,0 +1,8 @@
+package main
+
+func (r Read2) Read(p []byte) (n int, err error) {
+	panic("not implemented") // TODO: Implement
+}
+
+
+type Read2 struct{}
diff --git a/spec/fixtures/impl/writer_input.go b/spec/fixtures/impl/writer_input.go
new file mode 100644
index 0000000..ef034cc
--- /dev/null
+++ b/spec/fixtures/impl/writer_input.go
@@ -0,0 +1,3 @@
+package main
+
+type WriterTest struct{}
diff --git a/spec/fixtures/impl/writer_output.go b/spec/fixtures/impl/writer_output.go
new file mode 100644
index 0000000..19e8f6e
--- /dev/null
+++ b/spec/fixtures/impl/writer_output.go
@@ -0,0 +1,8 @@
+package main
+
+type WriterTest2 struct{}
+
+func (w *WriterTest2) Write(p []byte) (n int, err error) {
+	panic("not implemented") // TODO: Implement
+}
+
diff --git a/spec/integration/impl_test.lua b/spec/integration/impl_test.lua
index cf6620c..9ff57d8 100644
--- a/spec/integration/impl_test.lua
+++ b/spec/integration/impl_test.lua
@@ -10,9 +10,9 @@ local T = MiniTest.new_set {
   },
 }
 T["impl"] = MiniTest.new_set {}
-T["impl"]["works"] = function()
+T["impl"]["works w io.Writer"] = function()
   local tmp = t.tmpfile()
-  local fixtures = t.fixtures.read "impl/impl"
+  local fixtures = t.fixtures.read "impl/writer"
   t.fixtures.write(tmp, fixtures.input)
 
   child.cmd("silent edit " .. tmp)
@@ -21,7 +21,34 @@ T["impl"]["works"] = function()
   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")
+  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.fixtures.read "impl/reader"
+  t.fixtures.write(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.fixtures.read "impl/closer"
+  t.fixtures.write(tmp, fixtures.input)
+
+  child.cmd("silent edit " .. tmp)
+  child.fn.setpos(".", { child.fn.bufnr "%", 3, 6, 0 })
+  child.cmd "GoImpl io.Closer"
+  child.cmd "write"
+
+  local rhs = fixtures.output:gsub("Test2", "Test")
   t.eq(t.readfile(tmp), rhs)
 end
 
diff --git a/spec/integration/struct_tags_test.lua b/spec/integration/struct_tags_test.lua
index b0b1344..0d22a00 100644
--- a/spec/integration/struct_tags_test.lua
+++ b/spec/integration/struct_tags_test.lua
@@ -10,7 +10,7 @@ local T = MiniTest.new_set {
   },
 }
 T["struct_tags"] = MiniTest.new_set {}
-T["struct_tags"]["add"] = function()
+T["struct_tags"]["works add"] = function()
   local tmp = t.tmpfile()
   local fixtures = t.fixtures.read "tags/add"
   t.fixtures.write(tmp, fixtures.input)
@@ -22,7 +22,7 @@ T["struct_tags"]["add"] = function()
   t.eq(t.readfile(tmp), fixtures.output)
 end
 
-T["struct_tags"]["remove"] = function()
+T["struct_tags"]["works remove"] = function()
   local tmp = t.tmpfile()
   local fixtures = t.fixtures.read "tags/remove"
   t.fixtures.write(tmp, fixtures.input)