fix(Tags): tags option now updates existing tags correctly

alexcesaro#41

README.md

@@ -7,6 +7,8 @@ No releases but `master` will remain stable™.
 
 **Changelog**
 
+* 2020-08-27 - Fixed bug in `statsd.Tags` identified by https://github.com/alexcesaro/statsd/issues/41
+
 * 2019-05-22 - Added support for arbitrary output streams via new `statsd.WriteCloser` option
 
 * 2019-05-22 - Added support for simplified inline flush logic via new `statsd.InlineFlush` option

options.go

@@ -166,33 +166,19 @@ func Tags(tags ...string) Option {
 	if len(tags)%2 != 0 {
 		panic("statsd: Tags only accepts an even number of arguments")
 	}
-
-	return Option(func(c *config) {
-		if len(tags) == 0 {
-			return
-		}
-
-		newTags := make([]tag, len(tags)/2)
+	return func(c *config) {
+	UpdateLoop:
 		for i := 0; i < len(tags)/2; i++ {
-			newTags[i] = tag{K: tags[2*i], V: tags[2*i+1]}
-		}
-
-		for _, newTag := range newTags {
-			exists := false
-			for _, oldTag := range c.Client.Tags {
+			newTag := tag{K: tags[2*i], V: tags[2*i+1]}
+			for i, oldTag := range c.Client.Tags {
 				if newTag.K == oldTag.K {
-					exists = true
-					oldTag.V = newTag.V
+					c.Client.Tags[i] = newTag
+					continue UpdateLoop
 				}
 			}
-			if !exists {
-				c.Client.Tags = append(c.Client.Tags, tag{
-					K: newTag.K,
-					V: newTag.V,
-				})
-			}
+			c.Client.Tags = append(c.Client.Tags, newTag)
 		}
-	})
+	}
 }
 
 type tag struct {

statsd_test.go

@@ -340,17 +340,17 @@ func TestCloneRate(t *testing.T) {
 }
 
 func TestCloneInfluxDBTags(t *testing.T) {
-	testOutput(t, "test_key,tag1=value1,tag2=value2:5|c", func(c *Client) {
-		clone := c.Clone(Tags("tag1", "value3", "tag2", "value2"))
+	testOutput(t, "test_key,tag1=value3,tag3=value4,tag4=value9,tag5=value6,tag2=value2:5|c", func(c *Client) {
+		clone := c.Clone(Tags("tag2", "value2", "tag1", "value3", "tag4", "value8", "tag4", "value9"))
 		clone.Count(testKey, 5)
-	}, TagsFormat(InfluxDB), Tags("tag1", "value1"))
+	}, TagsFormat(InfluxDB), Tags("tag1", "value1", "tag3", "value4", "tag4", "value5", "tag5", "value6", "tag4", "value7"))
 }
 
 func TestCloneDatadogTags(t *testing.T) {
-	testOutput(t, "test_key:5|c|#tag1:value1,tag2:value2", func(c *Client) {
+	testOutput(t, "test_key:5|c|#tag1:value3,tag3:value4,tag2:value2", func(c *Client) {
 		clone := c.Clone(Tags("tag1", "value3", "tag2", "value2"))
 		clone.Count(testKey, 5)
-	}, TagsFormat(Datadog), Tags("tag1", "value1"))
+	}, TagsFormat(Datadog), Tags("tag1", "value1", "tag3", "value4"))
 }
 
 func TestDialError(t *testing.T) {
@@ -557,6 +557,7 @@ func mockUDPClosed(string, string, time.Duration) (net.Conn, error) {
 }
 
 func testClient(t *testing.T, f func(*Client), options ...Option) {
+	t.Helper()
 	dialTimeout = mockDial
 	defer func() { dialTimeout = net.DialTimeout }()
 
@@ -573,7 +574,9 @@ func testClient(t *testing.T, f func(*Client), options ...Option) {
 }
 
 func testOutput(t *testing.T, want string, f func(*Client), options ...Option) {
+	t.Helper()
 	testClient(t, func(c *Client) {
+		t.Helper()
 		f(c)
 		c.Close()