--- /dev/null
+[!gofumpt] skip 'don''t add or remove imports'
+
+gofumpt -w foo.go
+cmp foo.go foo.go.golden
+
+gofumpt -d foo.go.golden
+! stdout .
+
+-- foo.go --
+package p
+
+import "C"
+import "os"
+
+import "C"
+import (
+ "io"
+ "utf8"
+)
+
+-- foo.go.golden --
+package p
+
+import "C"
+import "os"
+
+import "C"
+import (
+ "io"
+ "utf8"
+)