Enable `go vet -unusedresult` check and fix warnings.

Makefile

@@ -1,5 +1,5 @@
 TEST?=$$(GO15VENDOREXPERIMENT=1 go list ./... | grep -v /vendor/)
-VETARGS?=-asmdecl -atomic -bool -buildtags -composites -copylocks -methods -nilfunc -printf -rangeloops -shift -structtags -unsafeptr
+VETARGS?=-asmdecl -atomic -bool -buildtags -composites -copylocks -methods -nilfunc -printf -rangeloops -shift -structtags -unsafeptr -unusedresult
 
 default: test
 

builtin/providers/azure/resource_azure_sql_database_server_test.go

@@ -81,7 +81,7 @@ func testAccCheckAzureSqlDatabaseServerDeleted(s *terraform.State) error {
 
 		for _, srv := range servers.DatabaseServers {
 			if srv.Name == resource.Primary.ID {
-				fmt.Errorf("SQL Server %s still exists.", resource.Primary.ID)
+				return fmt.Errorf("SQL Server %s still exists.", resource.Primary.ID)
 			}
 		}
 	}

builtin/providers/azure/resource_azure_sql_database_service_test.go

@@ -156,7 +156,7 @@ func testAccCheckAzureSqlDatabaseServiceDeleted(s *terraform.State) error {
 
 		for _, srv := range dbs.ServiceResources {
 			if srv.Name == resource.Primary.ID {
-				fmt.Errorf("SQL Service %s still exists.", resource.Primary.ID)
+				return fmt.Errorf("SQL Service %s still exists.", resource.Primary.ID)
 			}
 		}
 	}

builtin/providers/digitalocean/resource_digitalocean_floating_ip_test.go

@@ -61,7 +61,7 @@ func testAccCheckDigitalOceanFloatingIPDestroy(s *terraform.State) error {
 		_, _, err := client.FloatingIPs.Get(rs.Primary.ID)
 
 		if err == nil {
-			fmt.Errorf("Floating IP still exists")
+			return fmt.Errorf("Floating IP still exists")
 		}
 	}
 

builtin/providers/digitalocean/resource_digitalocean_ssh_key_test.go

@@ -51,7 +51,7 @@ func testAccCheckDigitalOceanSSHKeyDestroy(s *terraform.State) error {
 		_, _, err = client.Keys.GetByID(id)
 
 		if err == nil {
-			fmt.Errorf("SSH key still exists")
+			return fmt.Errorf("SSH key still exists")
 		}
 	}
 

builtin/providers/google/resource_pubsub_subscription_test.go

@@ -36,7 +36,7 @@ func testAccCheckPubsubSubscriptionDestroy(s *terraform.State) error {
 		config := testAccProvider.Meta().(*Config)
 		_, err := config.clientPubsub.Projects.Subscriptions.Get(rs.Primary.ID).Do()
 		if err != nil {
-			fmt.Errorf("Subscription still present")
+			return fmt.Errorf("Subscription still present")
 		}
 	}
 
@@ -56,7 +56,7 @@ func testAccPubsubSubscriptionExists(n string) resource.TestCheckFunc {
 		config := testAccProvider.Meta().(*Config)
 		_, err := config.clientPubsub.Projects.Subscriptions.Get(rs.Primary.ID).Do()
 		if err != nil {
-			fmt.Errorf("Subscription still present")
+			return fmt.Errorf("Subscription still present")
 		}
 
 		return nil

builtin/providers/google/resource_pubsub_topic_test.go

@@ -36,7 +36,7 @@ func testAccCheckPubsubTopicDestroy(s *terraform.State) error {
 		config := testAccProvider.Meta().(*Config)
 		_, err := config.clientPubsub.Projects.Topics.Get(rs.Primary.ID).Do()
 		if err != nil {
-			fmt.Errorf("Topic still present")
+			return fmt.Errorf("Topic still present")
 		}
 	}
 
@@ -56,7 +56,7 @@ func testAccPubsubTopicExists(n string) resource.TestCheckFunc {
 		config := testAccProvider.Meta().(*Config)
 		_, err := config.clientPubsub.Projects.Topics.Get(rs.Primary.ID).Do()
 		if err != nil {
-			fmt.Errorf("Topic still present")
+			return fmt.Errorf("Topic still present")
 		}
 
 		return nil

builtin/providers/tls/resource_cert_request.go

@@ -107,7 +107,7 @@ func CreateCertRequest(d *schema.ResourceData, meta interface{}) error {
 
 	certReqBytes, err := x509.CreateCertificateRequest(rand.Reader, &certReq, key)
 	if err != nil {
-		fmt.Errorf("Error creating certificate request: %s", err)
+		return fmt.Errorf("Error creating certificate request: %s", err)
 	}
 	certReqPem := string(pem.EncodeToMemory(&pem.Block{Type: pemCertReqType, Bytes: certReqBytes}))
 

builtin/providers/tls/resource_certificate.go

@@ -159,7 +159,7 @@ func createCertificate(d *schema.ResourceData, template, parent *x509.Certificat
 
 	certBytes, err := x509.CreateCertificate(rand.Reader, template, parent, pub, priv)
 	if err != nil {
-		fmt.Errorf("error creating certificate: %s", err)
+		return fmt.Errorf("error creating certificate: %s", err)
 	}
 	certPem := string(pem.EncodeToMemory(&pem.Block{Type: pemCertType, Bytes: certBytes}))