diff --git a/cloud.go b/cloud.go
index 6933633..2f10b6f 100644
--- a/cloud.go
+++ b/cloud.go
@@ -20,6 +20,7 @@ import (
 type Request struct {
 	Birthdays     bool
 	Anniversaries bool
+	DryRun        bool
 }
 
 var anniversariesWisher *internal.Wisher
@@ -44,8 +45,6 @@ func init() {
 	bambooDomain := MustEnv("BAMBOOHR_DOMAIN")
 	bambooToken := MustEnv("BAMBOOHR_TOKEN")
 
-	fmt.Printf("%+v", os.Environ())
-
 	slackClient := slack.New(slackToken, slack.OptionHTTPClient(&http.Client{Transport: &ochttp.Transport{}}))
 
 	slackNotifier := &internal.SlackNotifier{
@@ -85,7 +84,11 @@ func init() {
 func initTracing() {
 	var err error
 
-	projectID := MustEnv("GCP_PROJECT")
+	projectID := os.Getenv("GCP_PROJECT")
+
+	if projectID == "" {
+		return
+	}
 
 	exporter, err = stackdriver.NewExporter(stackdriver.Options{
 		ProjectID: projectID,
@@ -108,7 +111,9 @@ type PubSubMessage struct {
 func OnPubSubMessage(ctx context.Context, message PubSubMessage) error {
 	ctx, span := trace.StartSpan(ctx, "HappyTrigger")
 	defer span.End()
-	defer exporter.Flush()
+	if exporter != nil {
+		defer exporter.Flush()
+	}
 
 	var request Request
 	decoder := json.NewDecoder(bytes.NewReader(message.Data))
@@ -121,7 +126,7 @@ func OnPubSubMessage(ctx context.Context, message PubSubMessage) error {
 	employees := employeesRepository.List(ctx)
 
 	if request.Birthdays {
-		message, err := birthdaysWisher.Wish(ctx, currentDate, employees)
+		message, err := birthdaysWisher.Wish(ctx, currentDate, employees, request.DryRun)
 		if err != nil {
 			log.Print("Failed to wish birthdays")
 			return err
@@ -130,7 +135,7 @@ func OnPubSubMessage(ctx context.Context, message PubSubMessage) error {
 	}
 
 	if request.Anniversaries {
-		message, err := anniversariesWisher.Wish(ctx, currentDate, employees)
+		message, err := anniversariesWisher.Wish(ctx, currentDate, employees, request.DryRun)
 		if err != nil {
 			log.Print("Failed to wish anniversaries")
 			return err
diff --git a/cmd/main.go b/cmd/main.go
index 369f12d..1d6d6f1 100644
--- a/cmd/main.go
+++ b/cmd/main.go
@@ -16,7 +16,9 @@ func main() {
 		err = slackhappy.OnPubSubMessage(request.Context(), slackhappy.PubSubMessage{
 			Data: payload,
 		})
-		log.Printf("failed to process the PubSub message: %q", err)
+		if err != nil {
+			log.Printf("failed to process the PubSub message: %s", err)
+		}
 	})
 	log.Fatal(http.ListenAndServe("0.0.0.0:8889", nil))
 }
diff --git a/go.sum b/go.sum
index ad73209..b844a00 100644
--- a/go.sum
+++ b/go.sum
@@ -3,25 +3,31 @@ cloud.google.com/go v0.34.0/go.mod h1:aQUYkXzVsufM+DwF1aE+0xfcU+56JwCaLick0ClmMT
 cloud.google.com/go v0.38.0/go.mod h1:990N+gfupTy94rShfmMCWGDn0LpTmnzTp2qbd1dvSRU=
 cloud.google.com/go v0.44.1/go.mod h1:iSa0KzasP4Uvy3f1mN/7PiObzGgflwredwwASm/v6AU=
 cloud.google.com/go v0.44.2/go.mod h1:60680Gw3Yr4ikxnPRS/oxxkBccT6SA1yMk63TGekxKY=
+cloud.google.com/go v0.45.1 h1:lRi0CHyU+ytlvylOlFKKq0af6JncuyoRh1J+QJBqQx0=
 cloud.google.com/go v0.45.1/go.mod h1:RpBamKRgapWJb87xiFSdk4g1CME7QZg3uwTez+TSTjc=
 cloud.google.com/go/bigquery v1.0.1/go.mod h1:i/xbL2UlR5RvWAURpBYZTtm/cXjCha9lbfbpx4poX+o=
 cloud.google.com/go/datastore v1.0.0/go.mod h1:LXYbyblFSglQ5pkeyhO+Qmw7ukd3C+pD7TKLgZqpHYE=
+contrib.go.opencensus.io/exporter/stackdriver v0.13.0 h1:Jaz7WbqjtfoCPa1KbfisCX+P5aM3DizEY9pQMU0oAQo=
 contrib.go.opencensus.io/exporter/stackdriver v0.13.0/go.mod h1:z2tyTZtPmQ2HvWH4cOmVDgtY+1lomfKdbLnkJvZdc8c=
 github.com/BurntSushi/toml v0.3.1/go.mod h1:xHWCNGjB5oqiDr8zfno3MHue2Ht5sIBksp03qcyfWMU=
 github.com/BurntSushi/xgb v0.0.0-20160522181843-27f122750802/go.mod h1:IVnqGOEym/WlBOVXweHU+Q+/VP0lqqI8lqeDx9IjBqo=
+github.com/aws/aws-sdk-go v1.23.20 h1:2CBuL21P0yKdZN5urf2NxKa1ha8fhnY+A3pBCHFeZoA=
 github.com/aws/aws-sdk-go v1.23.20/go.mod h1:KmX6BPdI08NWTb3/sm4ZGu5ShLoqVDhKgpiN924inxo=
+github.com/census-instrumentation/opencensus-proto v0.2.1 h1:glEXhBS5PSLLv4IXzLA5yPRVX4bilULVyxxbrfOtDAk=
 github.com/census-instrumentation/opencensus-proto v0.2.1/go.mod h1:f6KPmirojxKA12rnyqOA5BBL4O983OfeGPqjHWSTneU=
 github.com/client9/misspell v0.3.4/go.mod h1:qj6jICC3Q7zFZvVWo7KLAzC3yx5G7kyvSDkc90ppPyw=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/golang/glog v0.0.0-20160126235308-23def4e6c14b/go.mod h1:SBH7ygxi8pfUlaOkMMuAQtPIUF8ecWP5IEl/CR7VP2Q=
+github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6 h1:ZgQEtGgCBiWRM39fZuwSd1LwSqqSW0hOdXCYYDX0R3I=
 github.com/golang/groupcache v0.0.0-20190702054246-869f871628b6/go.mod h1:cIg4eruTrX1D+g88fzRXU5OdNfaM+9IcxsU14FzY7Hc=
 github.com/golang/mock v1.1.1/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.2.0/go.mod h1:oTYuIxOrZwtPieC+H1uAHpcLFnEyAGVDL/k47Jfbm0A=
 github.com/golang/mock v1.3.1/go.mod h1:sBzyDLLjw3U8JLTeZvSv8jJB+tU5PVekmnlKIyFUx0Y=
 github.com/golang/protobuf v1.2.0/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/golang/protobuf v1.3.1/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
+github.com/golang/protobuf v1.3.2 h1:6nsPYzhq5kReh6QImI3k5qWzO4PEbvbIW2cwSfR/6xs=
 github.com/golang/protobuf v1.3.2/go.mod h1:6lQm79b+lXiMfvg/cZm0SGofjICqVBUtrP5yJMmIC1U=
 github.com/google/btree v0.0.0-20180813153112-4030bb1f1f0c/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
 github.com/google/btree v1.0.0/go.mod h1:lNA+9X1NB3Zf8V7Ke586lFgjr2dZNuvo3lPJSGZ5JPQ=
@@ -33,11 +39,13 @@ github.com/google/pprof v0.0.0-20181206194817-3ea8567a2e57/go.mod h1:zfwlbNMJ+OI
 github.com/google/pprof v0.0.0-20190515194954-54271f7e092f/go.mod h1:zfwlbNMJ+OItoe0UupaVj+oy1omPYYDuagoSzA8v9mc=
 github.com/google/renameio v0.1.0/go.mod h1:KWCgfxg9yswjAJkECMjeO8J8rahYeXnNhOm40UhjYkI=
 github.com/googleapis/gax-go/v2 v2.0.4/go.mod h1:0Wqv26UfaUD9n4G6kQubkQ+KchISgw+vpHVxEJEs9eg=
+github.com/googleapis/gax-go/v2 v2.0.5 h1:sjZBwGj9Jlw33ImPtvFviGYvseOtDM7hkSKB7+Tv3SM=
 github.com/googleapis/gax-go/v2 v2.0.5/go.mod h1:DWXyrwAJ9X0FpwwEdw+IPEYBICEFu5mhpdKc/us6bOk=
 github.com/gorilla/websocket v1.2.0 h1:VJtLvh6VQym50czpZzx07z/kw9EgAxI3x1ZB8taTMQQ=
 github.com/gorilla/websocket v1.2.0/go.mod h1:E7qHFY5m1UJ88s3WnNqhKjPHQ0heANvMoAMk2YaljkQ=
 github.com/hashicorp/golang-lru v0.5.0/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
 github.com/hashicorp/golang-lru v0.5.1/go.mod h1:/m3WP610KZHVQ1SGc6re/UDhFvYD7pJ4Ao+sR/qLZy8=
+github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af h1:pmfjZENx5imkbgOkpRUYLnmbU7UEFbjtDA2hxJ1ichM=
 github.com/jmespath/go-jmespath v0.0.0-20180206201540-c2b33e8439af/go.mod h1:Nht3zPeWKUH0NzdCt2Blrr5ys8VGpn0CEB0cQHVjt7k=
 github.com/jstemmer/go-junit-report v0.0.0-20190106144839-af01ea7f8024/go.mod h1:6v2b51hI/fHJwM22ozAgKL4VKDeJcHhJFhtBdhmNjmU=
 github.com/kisielk/gotool v1.0.0/go.mod h1:XhKaO+MFFWcvkIS/tQcRk01m1F5IRFswLeQ+oQHNcck=
@@ -58,6 +66,7 @@ github.com/stretchr/testify v1.4.0 h1:2E4SXV/wtOkTonXsotYi4li6zVWxYlZuYNCXe9XRJy
 github.com/stretchr/testify v1.4.0/go.mod h1:j7eGeouHqKxXV5pUuKE4zz7dFj8WfuZ+81PSLYec5m4=
 go.opencensus.io v0.21.0/go.mod h1:mSImk1erAIZhrmZN+AvHh14ztQfjbGwt4TtuofqLduU=
 go.opencensus.io v0.22.0/go.mod h1:+kGneAE2xo2IficOXnaByMWTGM9T73dGwxeWcUqIpI8=
+go.opencensus.io v0.22.1 h1:8dP3SGL7MPB94crU3bEPplMPe83FI4EouesJUeFHv50=
 go.opencensus.io v0.22.1/go.mod h1:Ap50jQcDJrx6rB6VgeeFPtuPIf3wMRvRfrfYDO6+BmA=
 golang.org/x/crypto v0.0.0-20190308221718-c2843e01d9a2/go.mod h1:djNgcEr1/C05ACkg1iLfiJU5Ep61QUkGW8qpdssI0+w=
 golang.org/x/crypto v0.0.0-20190510104115-cbcb75029529/go.mod h1:yigFU9vqHzYiE8UmvKecakEJjdnWj3jj499lnFckfCI=
@@ -82,15 +91,18 @@ golang.org/x/net v0.0.0-20190501004415-9ce7a6920f09/go.mod h1:t9HGtf8HONx5eT2rtn
 golang.org/x/net v0.0.0-20190503192946-f4e77d36d62c/go.mod h1:t9HGtf8HONx5eT2rtn7q6eTqICYqUVnKs3thJo3Qplg=
 golang.org/x/net v0.0.0-20190603091049-60506f45cf65/go.mod h1:HSz+uSET+XFnRR8LxR5pz3Of3rY3CfYBVs4xY44aLks=
 golang.org/x/net v0.0.0-20190620200207-3b0461eec859/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
+golang.org/x/net v0.0.0-20190923162816-aa69164e4478 h1:l5EDrHhldLYb3ZRHDUhXF7Om7MvYXnkV9/iQNo1lX6g=
 golang.org/x/net v0.0.0-20190923162816-aa69164e4478/go.mod h1:z5CRVTTTmAJ677TzLLGU+0bjPO0LkuOLi4/5GtJWs/s=
 golang.org/x/oauth2 v0.0.0-20180821212333-d2e6202438be/go.mod h1:N/0e6XlmueqKjAGxoOufVs8QHGRruUQn6yWY3a++T0U=
 golang.org/x/oauth2 v0.0.0-20190226205417-e64efc72b421/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
+golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45 h1:SVwTIAaPC2U/AvvLNZ2a7OVsmBpC8L5BlwK1whH3hm0=
 golang.org/x/oauth2 v0.0.0-20190604053449-0f29369cfe45/go.mod h1:gOpvHmFTYa4IltrdGE7lF6nIHvwfUNPOp7c8zoXwtLw=
 golang.org/x/sync v0.0.0-20180314180146-1d60e4601c6f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181108010431-42b317875d0f/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20181221193216-37e7f081c4d4/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190227155943-e225da77a7e6/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sync v0.0.0-20190423024810-112230192c58/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
+golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e h1:vcxGaoTs7kV8m5Np9uUNQin4BrLOthgV7252N8V+FwY=
 golang.org/x/sync v0.0.0-20190911185100-cd5d95a43a6e/go.mod h1:RxMgew5VJxzue5/jJTE5uejpjVlOe/izrB70Jof72aM=
 golang.org/x/sys v0.0.0-20180830151530-49385e6e1522/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
 golang.org/x/sys v0.0.0-20190215142949-d0b11bdaac8a/go.mod h1:STP8DvDyc/dI5b8T5hshtkjS+E42TnysNCUPdjciGhY=
@@ -102,6 +114,7 @@ golang.org/x/sys v0.0.0-20190606165138-5da285871e9c/go.mod h1:h1NjWce9XRLGQEsW7w
 golang.org/x/sys v0.0.0-20190624142023-c5567b49c5d0/go.mod h1:h1NjWce9XRLGQEsW7wpKNCjG9DtNlClVuFLEZdDNbEs=
 golang.org/x/text v0.3.0/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
 golang.org/x/text v0.3.1-0.20180807135948-17ff2d5776d2/go.mod h1:NqM8EUOU14njkJ3fqMW+pc6Ldnwhi/IjpwHt7yyuwOQ=
+golang.org/x/text v0.3.2 h1:tW2bmiBqwgJj/UpqtC8EpXEZVYOwU0yG4iWbprSVAcs=
 golang.org/x/text v0.3.2/go.mod h1:bEr9sfX3Q8Zfm5fL9x+3itogRgK3+ptLWKqgva+5dAk=
 golang.org/x/time v0.0.0-20181108054448-85acf8d2951c/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
 golang.org/x/time v0.0.0-20190308202827-9d24e82272b4/go.mod h1:tRJNPiyCQ0inRvYxbN9jk5I+vvW/OXSQhTDSoE431IQ=
@@ -123,6 +136,7 @@ google.golang.org/api v0.4.0/go.mod h1:8k5glujaEP+g9n7WNsDg8QP6cUVNI86fCNMcbazEt
 google.golang.org/api v0.7.0/go.mod h1:WtwebWUNSVBH/HAw79HIFXZNqEvBhG+Ra+ax0hx3E3M=
 google.golang.org/api v0.8.0/go.mod h1:o4eAsZoiT+ibD93RtjEohWalFOjRDx6CVaqeizhEnKg=
 google.golang.org/api v0.9.0/go.mod h1:o4eAsZoiT+ibD93RtjEohWalFOjRDx6CVaqeizhEnKg=
+google.golang.org/api v0.10.0 h1:7tmAxx3oKE98VMZ+SBZzvYYWRQ9HODBxmC8mXUsraSQ=
 google.golang.org/api v0.10.0/go.mod h1:o4eAsZoiT+ibD93RtjEohWalFOjRDx6CVaqeizhEnKg=
 google.golang.org/appengine v1.1.0/go.mod h1:EbEs0AVv82hx2wNQdGPgUI5lhzA/G0D9YwlJXL52JkM=
 google.golang.org/appengine v1.4.0/go.mod h1:xpcJRLb0r/rnEns0DIKYYv+WjYCduHsrkT7/EB5XEv4=
@@ -136,10 +150,12 @@ google.golang.org/genproto v0.0.0-20190425155659-357c62f0e4bb/go.mod h1:VzzqZJRn
 google.golang.org/genproto v0.0.0-20190502173448-54afdca5d873/go.mod h1:VzzqZJRnGkLBvHegQrXjBqPurQTc5/KpmUdxsrq26oE=
 google.golang.org/genproto v0.0.0-20190801165951-fa694d86fc64/go.mod h1:DMBHOl98Agz4BDEuKkezgsaosCRResVns1a3J2ZsMNc=
 google.golang.org/genproto v0.0.0-20190819201941-24fa4b261c55/go.mod h1:DMBHOl98Agz4BDEuKkezgsaosCRResVns1a3J2ZsMNc=
+google.golang.org/genproto v0.0.0-20190911173649-1774047e7e51 h1:Ex1mq5jaJof+kRnYi3SlYJ8KKa9Ao3NHyIT5XJ1gF6U=
 google.golang.org/genproto v0.0.0-20190911173649-1774047e7e51/go.mod h1:IbNlFCBrqXvoKpeg0TB2l7cyZUmoaFKYIwrEpbDKLA8=
 google.golang.org/grpc v1.19.0/go.mod h1:mqu4LbDTu4XGKhr4mRzUsmM4RtVoemTSY81AxZiDr8c=
 google.golang.org/grpc v1.20.1/go.mod h1:10oTOabMzJvdu6/UiuZezV6QK5dSlG84ov/aaiqXj38=
 google.golang.org/grpc v1.21.1/go.mod h1:oYelfM1adQP15Ek0mdvEgi9Df8B9CZIaU1084ijfRaM=
+google.golang.org/grpc v1.23.1 h1:q4XQuHFC6I28BKZpo6IYyb3mNO+l7lSOxRuYTCiDfXk=
 google.golang.org/grpc v1.23.1/go.mod h1:Y5yQAOtifL1yxbo5wqy6BxZv8vAUGQwXBOALyacEbxg=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405 h1:yhCVgyC4o1eVCa2tZl7eS0r+SDo693bJlVdllGtEeKM=
 gopkg.in/check.v1 v0.0.0-20161208181325-20d25e280405/go.mod h1:Co6ibVJAznAaIkqp8huTwlJQCZ016jof/cbN4VW5Yz0=
diff --git a/internal/repository.go b/internal/repository.go
index 06b6f2b..e898b72 100644
--- a/internal/repository.go
+++ b/internal/repository.go
@@ -28,7 +28,7 @@ func (b *BambooRepository) List(ctx context.Context) []Employee {
 
 		hireDate, err := time.Parse("2006-01-02", employee["hireDate"])
 		if err != nil {
-			fmt.Printf("invalid hireDate %q", employee["hireDate"])
+			fmt.Printf("invalid hireDate %q\n", employee["hireDate"])
 			continue
 		}
 
diff --git a/internal/wish.go b/internal/wish.go
index ab596a0..af094fd 100644
--- a/internal/wish.go
+++ b/internal/wish.go
@@ -3,6 +3,7 @@ package internal
 import (
 	"context"
 	"fmt"
+	"log"
 	"sort"
 	"time"
 )
@@ -14,7 +15,7 @@ type Wisher struct {
 	Notifier        Notifier
 }
 
-func (w Wisher) Wish(ctx context.Context, date time.Time, employees []Employee) (string, error) {
+func (w Wisher) Wish(ctx context.Context, date time.Time, employees []Employee, dryRun bool) (string, error) {
 	filtered := Filter(employees, func(employee Employee) bool {
 		return w.FilterPredicate(employee, date)
 	})
@@ -27,9 +28,14 @@ func (w Wisher) Wish(ctx context.Context, date time.Time, employees []Employee)
 
 	message := w.Formatter.Format(names)
 
-	err := w.Notifier.Notify(ctx, message)
-	if err != nil {
-		return "", err
+	if dryRun {
+		log.Println("Dry-run: no message sent")
+	} else {
+		log.Printf("Sending message: %q", message)
+		err := w.Notifier.Notify(ctx, message)
+		if err != nil {
+			return "", err
+		}
 	}
 
 	return message, nil
diff --git a/internal/wish_test.go b/internal/wish_test.go
index 704158a..727d377 100644
--- a/internal/wish_test.go
+++ b/internal/wish_test.go
@@ -32,7 +32,7 @@ func TestWisher_Wish_EmptyMessage(t *testing.T) {
 		Notifier:     nil,
 	}
 
-	result, err := wisher.Wish(context.Background(), time.Now(), employees)
+	result, err := wisher.Wish(context.Background(), time.Now(), employees, false)
 
 	assert.Nil(t, err)
 	assert.Equal(t, "Empty", result)
@@ -49,7 +49,7 @@ func TestWisher_Wish_All(t *testing.T) {
 		Notifier:     fakeNotifier,
 	}
 
-	result, err := wisher.Wish(context.Background(), time.Now(), employees)
+	result, err := wisher.Wish(context.Background(), time.Now(), employees, false)
 
 	assert.Nil(t, err)
 	assert.Equal(t, "Prefix Emily Brow, John Doe, Stephanie Wilson Suffix", result)
@@ -67,9 +67,27 @@ func TestWisher_Wish_Birthdays(t *testing.T) {
 		Notifier:     fakeNotifier,
 	}
 
-	result, err := wisher.Wish(context.Background(), MustParseTime("2006-01-02", "2020-03-14"), employees)
+	result, err := wisher.Wish(context.Background(), MustParseTime("2006-01-02", "2020-03-14"), employees, false)
 
 	assert.Nil(t, err)
 	assert.Equal(t, "Prefix Emily Brow, Stephanie Wilson Suffix", result)
 	assert.Equal(t, "Prefix Emily Brow, Stephanie Wilson Suffix", fakeNotifier.Message)
 }
+
+func TestWisher_Wish_Birthdays_DryRun(t *testing.T) {
+	fakeNotifier := &FakeNotifier{}
+	wisher := Wisher{
+		FilterPredicate: func(employee Employee, date time.Time) bool {
+			return employee.IsBirthday(date)
+		},
+		Formatter:    SimpleFormatter{Prefix: "Prefix", Suffix: "Suffix"},
+		EmptyMessage: "Empty",
+		Notifier:     fakeNotifier,
+	}
+
+	result, err := wisher.Wish(context.Background(), MustParseTime("2006-01-02", "2020-03-14"), employees, true)
+
+	assert.Nil(t, err)
+	assert.Equal(t, "Prefix Emily Brow, Stephanie Wilson Suffix", result)
+	assert.Equal(t, "", fakeNotifier.Message)
+}