From f1e92163a561624a19e9ef3f6115908e7e005899 Mon Sep 17 00:00:00 2001
From: Kevin Hoffman <autodidaddict@users.noreply.github.com>
Date: Wed, 28 Feb 2024 10:06:44 -0500
Subject: [PATCH] adds a keys method to header

Signed-off-by: Kevin Hoffman <autodidaddict@users.noreply.github.com>
---
 nats.go      | 11 +++++++++++
 nats_test.go | 20 ++++++++++++++++++++
 2 files changed, 31 insertions(+)

diff --git a/nats.go b/nats.go
index 0be428932..3bd646662 100644
--- a/nats.go
+++ b/nats.go
@@ -3640,6 +3640,17 @@ func (h Header) Get(key string) string {
 	return _EMPTY_
 }
 
+// Returns the list of keys in the message header
+func (h Header) Keys() []string {
+	keys := make([]string, len(h))
+	i := 0
+	for k := range h {
+		keys[i] = k
+		i++
+	}
+	return keys
+}
+
 // Values returns all values associated with the given key.
 // It is case-sensitive.
 func (h Header) Values(key string) []string {
diff --git a/nats_test.go b/nats_test.go
index 7dcdce2cf..a2f34d86a 100644
--- a/nats_test.go
+++ b/nats_test.go
@@ -29,6 +29,7 @@ import (
 	"reflect"
 	"regexp"
 	"runtime"
+	"slices"
 	"strconv"
 	"strings"
 	"sync"
@@ -1593,6 +1594,25 @@ func TestHeaderParser(t *testing.T) {
 	checkStatus("NATS/1.0  404   No Messages", 404, "No Messages")
 }
 
+func TestHeaderKeys(t *testing.T) {
+	m := NewMsg("testing")
+	m.Header = Header{
+		"field1": []string{"a"},
+		"field2": []string{"b"},
+	}
+	actualKeys := m.Header.Keys()
+	if !slices.Contains(actualKeys, "field1") ||
+		!slices.Contains(actualKeys, "field2") {
+		t.Fatalf("Keys did not return expected list: %+v", actualKeys)
+	}
+
+	m.Header = Header{}
+	emptyKeys := m.Header.Keys()
+	if len(emptyKeys) > 0 {
+		t.Fatal("Empty header should've returned empty keys list")
+	}
+}
+
 func TestHeaderMultiLine(t *testing.T) {
 	m := NewMsg("foo")
 	m.Header = Header{