Add more tests around trailing-newlines from the encoder

1 files changed, 33 insertions, 9 deletions

diff --git a/encode.go b/encode.go
index a77d8aa..44fd985 100644
--- a/encode.go
+++ b/encode.go
@@ -40,8 +40,25 @@ func encodeWriteString(w io.Writer, str string) {
 }
 
 type Encoder struct {
-	W               io.Writer
-	BackslashEscape BackslashEscaper
+	w *ReEncoder
+}
+
+// NewEncoder returns a new encoder.
+//
+// If w is an *ReEncoder, then the inner backslash-escaping of
+// double-encoded ",string" tagged string values obeys the
+// *ReEncoder's BackslashEscape policy.
+func NewEncoder(w io.Writer) *Encoder {
+	re, ok := w.(*ReEncoder)
+	if !ok {
+		re = &ReEncoder{
+			Out:                 w,
+			AllowMultipleValues: true,
+		}
+	}
+	return &Encoder{
+		w: re,
+	}
 }
 
 func (enc *Encoder) Encode(obj any) (err error) {
@@ -54,16 +71,21 @@ func (enc *Encoder) Encode(obj any) (err error) {
 			}
 		}
 	}()
-	encode(enc.W, reflect.ValueOf(obj), enc.BackslashEscape, false, 0, map[any]struct{}{})
-	if f, ok := enc.W.(interface{ Flush() error }); ok {
-		return f.Flush()
-	}
-	return nil
+	encode(enc.w, reflect.ValueOf(obj), enc.w.BackslashEscape, false, 0, map[any]struct{}{})
+	return enc.w.Close()
 }
 
+// Encode encodes a value to w.
+//
+// If w is an *ReEncoder, then the inner backslash-escaping of
+// double-encoded ",string" tagged string values obeys the
+// *ReEncoder's BackslashEscape policy.
+//
+// Does not write a trailing newline or other whitespace; if you will
+// be encoding multiple values to w, then you should instead use an
+// *Encoder object, as some JSON values need whitespace between them.
 func Encode(w io.Writer, obj any) (err error) {
-	enc := &Encoder{W: w}
-	return enc.Encode(obj)
+	return NewEncoder(w).Encode(obj)
 }
 
 var (
@@ -94,6 +116,7 @@ func encode(w io.Writer, val reflect.Value, escaper BackslashEscaper, quote bool
 			encodeWriteString(w, "null")
 			return
 		}
+		// Use a sub-ReEncoder to check that it's a full element.
 		validator := &ReEncoder{Out: w, BackslashEscape: escaper}
 		if err := obj.EncodeJSON(validator); err != nil {
 			panic(encodeError{&EncodeMethodError{
@@ -127,6 +150,7 @@ func encode(w io.Writer, val reflect.Value, escaper BackslashEscaper, quote bool
 				SourceFunc: "MarshalJSON",
 			}})
 		}
+		// Use a sub-ReEncoder to check that it's a full element.
 		validator := &ReEncoder{Out: w, BackslashEscape: escaper}
 		if _, err := validator.Write(dat); err != nil {
 			panic(encodeError{err})