move error_accumulator into internal pkg (#304) (#335)

* move error_accumulator into internal pkg (#304)

* move error_accumulator into internal pkg (#304)

* add a test for ErrTooManyEmptyStreamMessages in stream_reader (#304)

internal/error_accumulator_test.go

@@ -0,0 +1,41 @@
+package openai_test
+
+import (
+	"bytes"
+	"errors"
+	"testing"
+
+	utils "github.com/sashabaranov/go-openai/internal"
+	"github.com/sashabaranov/go-openai/internal/test"
+)
+
+func TestErrorAccumulatorBytes(t *testing.T) {
+	accumulator := &utils.DefaultErrorAccumulator{
+		Buffer: &bytes.Buffer{},
+	}
+
+	errBytes := accumulator.Bytes()
+	if len(errBytes) != 0 {
+		t.Fatalf("Did not return nil with empty bytes: %s", string(errBytes))
+	}
+
+	err := accumulator.Write([]byte("{}"))
+	if err != nil {
+		t.Fatalf("%+v", err)
+	}
+
+	errBytes = accumulator.Bytes()
+	if len(errBytes) == 0 {
+		t.Fatalf("Did not return error bytes when has error: %s", string(errBytes))
+	}
+}
+
+func TestErrorByteWriteErrors(t *testing.T) {
+	accumulator := &utils.DefaultErrorAccumulator{
+		Buffer: &test.FailingErrorBuffer{},
+	}
+	err := accumulator.Write([]byte("{"))
+	if !errors.Is(err, test.ErrTestErrorAccumulatorWriteFailed) {
+		t.Fatalf("Did not return error when write failed: %v", err)
+	}
+}