test button.plaintext parser

src/device/input/button/plaintext.go

@@ -6,26 +6,29 @@ import (
 )
 
 type Plaintext struct {
-	src raw.Raw
+	src     raw.Raw
+	release byte
 }
 
 func NewPlaintext(src raw.Raw) Plaintext {
-	return Plaintext{src: src}
+	releaseChar := byte('!')
+	if v := os.Getenv("BUTTON_PLAINTEXT_RELEASE"); v != "" {
+		releaseChar = byte(v[0])
+	}
+	return Plaintext{
+		src:     src,
+		release: releaseChar,
+	}
 }
 
 func (p Plaintext) Close() { p.src.Close() }
 
 func (p Plaintext) Read() []Button {
-	releaseChar := byte('!')
-	if v := os.Getenv("BUTTON_PLAINTEXT_RELEASE"); v != "" {
-		releaseChar = byte(v[0])
-	}
-
 	b := p.src.Read()
 	buttons := make([]Button, 0, len(b))
 	down := true
 	for i := range b {
-		if b[i] == releaseChar {
+		if b[i] == p.release {
 			down = false
 		} else {
 			if b[i] != '\n' {