diff --git a/.github/workflows/pr.yml b/.github/workflows/pr.yml
index 79ad56aca..b1292eb9b 100644
--- a/.github/workflows/pr.yml
+++ b/.github/workflows/pr.yml
@@ -3,4 +3,4 @@ on:
   pull_request:
 jobs:
   ci:
-    uses: ThreeDotsLabs/watermill/.github/workflows/tests.yml@lint
+    uses: ThreeDotsLabs/watermill/.github/workflows/tests.yml@codeconv-pr
diff --git a/.github/workflows/tests.yml b/.github/workflows/tests.yml
index 24577668a..b71a22dc6 100644
--- a/.github/workflows/tests.yml
+++ b/.github/workflows/tests.yml
@@ -43,3 +43,12 @@ jobs:
       - run: make test_stress
         if: ${{ inputs.stress-tests }}
 
+  codecov:
+    runs-on: ubuntu-latest
+    steps:
+      - uses: actions/checkout@master
+      - uses: actions/setup-go@v2
+        with:
+          go-version: '^1.21.1'
+      - run: make test_codecov
+      - uses: codecov/codecov-action@v3
diff --git a/components/requestreply/backend_pubsub.go b/components/requestreply/backend_pubsub.go
index d5352b9e2..d6fb90a5d 100644
--- a/components/requestreply/backend_pubsub.go
+++ b/components/requestreply/backend_pubsub.go
@@ -7,6 +7,7 @@ import (
 
 	"github.com/ThreeDotsLabs/watermill"
 	"github.com/ThreeDotsLabs/watermill/message"
+	"github.com/hashicorp/go-multierror"
 	"github.com/pkg/errors"
 )
 
@@ -97,20 +98,22 @@ func (p *PubSubBackendConfig) setDefaults() {
 }
 
 func (p *PubSubBackendConfig) Validate() error {
+	var err error
+
 	if p.Publisher == nil {
-		return errors.New("publisher cannot be nil")
+		err = multierror.Append(err, errors.New("publisher cannot be nil"))
 	}
 	if p.SubscriberConstructor == nil {
-		return errors.New("subscriber constructor cannot be nil")
+		err = multierror.Append(err, errors.New("subscriber constructor cannot be nil"))
 	}
 	if p.GeneratePublishTopic == nil {
-		return errors.New("GeneratePublishTopic cannot be nil")
+		err = multierror.Append(err, errors.New("GeneratePublishTopic cannot be nil"))
 	}
 	if p.GenerateSubscribeTopic == nil {
-		return errors.New("GenerateSubscribeTopic cannot be nil")
+		err = multierror.Append(err, errors.New("GenerateSubscribeTopic cannot be nil"))
 	}
 
-	return nil
+	return err
 }
 
 func (p PubSubBackend[Result]) ListenForNotifications(
diff --git a/components/requestreply/requestreply_test.go b/components/requestreply/requestreply_test.go
index 690ebd290..a323b172f 100644
--- a/components/requestreply/requestreply_test.go
+++ b/components/requestreply/requestreply_test.go
@@ -28,6 +28,7 @@ type TestServices[Result any] struct {
 	CommandProcessor *cqrs.CommandProcessor
 
 	RequestReplyBackend *requestreply.PubSubBackend[Result]
+	BackendConfig       requestreply.PubSubBackendConfig
 }
 
 type TestServicesConfig struct {
@@ -50,47 +51,48 @@ func NewTestServices[Result any](t *testing.T, c TestServicesConfig) TestService
 		logger,
 	)
 
-	backend, err := requestreply.NewPubSubBackend[Result](
-		requestreply.PubSubBackendConfig{
-			Publisher: pubSub,
-			SubscriberConstructor: func(subscriberContext requestreply.PubSubBackendSubscribeParams) (message.Subscriber, error) {
-				assert.NotEmpty(t, subscriberContext.OperationID)
-				assert.NotEmpty(t, subscriberContext.Command)
+	backendConfig := requestreply.PubSubBackendConfig{
+		Publisher: pubSub,
+		SubscriberConstructor: func(subscriberContext requestreply.PubSubBackendSubscribeParams) (message.Subscriber, error) {
+			assert.NotEmpty(t, subscriberContext.OperationID)
+			assert.NotEmpty(t, subscriberContext.Command)
 
-				return pubSub, nil
-			},
-			GenerateSubscribeTopic: func(subscriberContext requestreply.PubSubBackendSubscribeParams) (string, error) {
-				assert.NotEmpty(t, subscriberContext.OperationID)
-				assert.NotEmpty(t, subscriberContext.Command)
+			return pubSub, nil
+		},
+		GenerateSubscribeTopic: func(subscriberContext requestreply.PubSubBackendSubscribeParams) (string, error) {
+			assert.NotEmpty(t, subscriberContext.OperationID)
+			assert.NotEmpty(t, subscriberContext.Command)
 
-				return "reply", nil
-			},
-			GeneratePublishTopic: func(subscriberContext requestreply.PubSubBackendPublishParams) (string, error) {
-				assert.NotEmpty(t, subscriberContext.OperationID)
-				assert.NotEmpty(t, subscriberContext.Command)
-				assert.NotEmpty(t, subscriberContext.CommandMessage)
+			return "reply", nil
+		},
+		GeneratePublishTopic: func(subscriberContext requestreply.PubSubBackendPublishParams) (string, error) {
+			assert.NotEmpty(t, subscriberContext.OperationID)
+			assert.NotEmpty(t, subscriberContext.Command)
+			assert.NotEmpty(t, subscriberContext.CommandMessage)
 
-				return "reply", nil
-			},
-			Logger: logger,
-			ModifyNotificationMessage: func(msg *message.Message, params requestreply.PubSubBackendOnCommandProcessedParams) error {
-				// to make it deterministic
-				msg.UUID = "1"
-
-				assert.NotEmpty(t, params.OperationID)
-				assert.NotEmpty(t, params.Command)
-				assert.NotEmpty(t, params.CommandMessage)
-
-				// to ensure backward compatibility
-				if c.AssertNotificationMessage != nil {
-					c.AssertNotificationMessage(t, msg)
-				}
+			return "reply", nil
+		},
+		Logger: logger,
+		ModifyNotificationMessage: func(msg *message.Message, params requestreply.PubSubBackendOnCommandProcessedParams) error {
+			// to make it deterministic
+			msg.UUID = "1"
 
-				return nil
-			},
-			AckCommandErrors:      !c.DoNotAckOnCommandErrors,
-			ListenForReplyTimeout: c.ListenForReplyTimeout,
+			assert.NotEmpty(t, params.OperationID)
+			assert.NotEmpty(t, params.Command)
+			assert.NotEmpty(t, params.CommandMessage)
+
+			// to ensure backward compatibility
+			if c.AssertNotificationMessage != nil {
+				c.AssertNotificationMessage(t, msg)
+			}
+
+			return nil
 		},
+		AckCommandErrors:      !c.DoNotAckOnCommandErrors,
+		ListenForReplyTimeout: c.ListenForReplyTimeout,
+	}
+	backend, err := requestreply.NewPubSubBackend[Result](
+		backendConfig,
 		requestreply.BackendPubsubJSONMarshaler[Result]{},
 	)
 	require.NoError(t, err)
@@ -130,6 +132,7 @@ func NewTestServices[Result any](t *testing.T, c TestServicesConfig) TestService
 		CommandBus:          commandBus,
 		CommandProcessor:    commandProcessor,
 		Marshaler:           marshaler,
+		BackendConfig:       backendConfig,
 	}
 }
 
@@ -733,3 +736,31 @@ func TestRequestReply_parallel_same_handler(t *testing.T) {
 	close(start)
 	wg.Wait()
 }
+
+func TestNewPubSubBackend_missing_values(t *testing.T) {
+	t.Run("invalid_config", func(t *testing.T) {
+		invalidConfig := requestreply.PubSubBackendConfig{}
+		require.Error(t, invalidConfig.Validate())
+
+		backend, err := requestreply.NewPubSubBackend[requestreply.NoResult](
+			invalidConfig,
+			requestreply.BackendPubsubJSONMarshaler[requestreply.NoResult]{},
+		)
+		assert.Error(t, err)
+		assert.ErrorContains(t, err, "invalid config")
+		assert.Nil(t, backend)
+	})
+
+	t.Run("missing_marshaler", func(t *testing.T) {
+		ts := NewTestServices[struct{}](t, TestServicesConfig{})
+		require.NoError(t, ts.BackendConfig.Validate())
+
+		backend, err := requestreply.NewPubSubBackend[requestreply.NoResult](
+			ts.BackendConfig,
+			nil,
+		)
+		assert.Error(t, err)
+		assert.ErrorContains(t, err, "marshaler cannot be nil")
+		assert.Nil(t, backend)
+	})
+}