added test to ensure json keys remain in order

pkg/yqlib/encoder_test.go

@@ -0,0 +1,44 @@
+package yqlib
+
+import (
+	"bufio"
+	"bytes"
+	"strings"
+	"testing"
+
+	"github.com/mikefarah/yq/v4/test"
+)
+
+var sampleYaml = `zabbix: winner
+apple: great
+banana:
+- {cobra: kai, angus: bob}
+`
+
+var expectedJson = `{
+  "zabbix": "winner",
+  "apple": "great",
+  "banana": [
+    {
+      "cobra": "kai",
+      "angus": "bob"
+    }
+  ]
+}
+`
+
+func TestJsonEncoderPreservesObjectOrder(t *testing.T) {
+	var output bytes.Buffer
+	writer := bufio.NewWriter(&output)
+
+	var jsonEncoder = NewJsonEncoder(writer, 2)
+	inputs, err := readDocuments(strings.NewReader(sampleYaml), "sample.yml")
+	if err != nil {
+		panic(err)
+	}
+	node := inputs.Front().Value.(*CandidateNode).Node
+	jsonEncoder.Encode(node)
+	writer.Flush()
+	test.AssertResult(t, expectedJson, output.String())
+
+}