integration: Validate that email integration has email

Add validation that iff email integration is used that an email
address is specified. Make a plan only change to trigger an error
and a diff.

pagerduty/resource_pagerduty_service_integration.go

@@ -17,6 +17,13 @@ func resourcePagerDutyServiceIntegration() *schema.Resource {
 		Read:   resourcePagerDutyServiceIntegrationRead,
 		Update: resourcePagerDutyServiceIntegrationUpdate,
 		Delete: resourcePagerDutyServiceIntegrationDelete,
+		CustomizeDiff: func(diff *schema.ResourceDiff, i interface{}) error {
+			t := diff.Get("type").(string)
+			if t == "generic_email_inbound_integration" && diff.Get("integration_email").(string) == "" {
+				return fmt.Errorf("integration_email attribute must be set for an integration type generic_email_inbound_integration")
+			}
+			return nil
+		},
 		Importer: &schema.ResourceImporter{
 			State: resourcePagerDutyServiceIntegrationImport,
 		},

pagerduty/resource_pagerduty_service_integration_test.go

@@ -2,6 +2,7 @@ package pagerduty
 
 import (
 	"fmt"
+	"regexp"
 	"testing"
 
 	"github.com/hashicorp/terraform-plugin-sdk/helper/acctest"
@@ -86,6 +87,20 @@ func TestAccPagerDutyServiceIntegrationGeneric_Basic(t *testing.T) {
 						"pagerduty_service_integration.foo", "type", "generic_events_api_inbound_integration"),
 				),
 			},
+			{
+				Config:      testAccCheckPagerDutyServiceIntegrationGenericEmail(username, email, escalationPolicy, service, serviceIntegration, ""),
+				PlanOnly:    true,
+				ExpectError: regexp.MustCompile("integration_email attribute must be set for an integration type generic_email_inbound_integration"),
+			},
+			{
+				Config: testAccCheckPagerDutyServiceIntegrationGenericEmail(username, email, escalationPolicy, service, serviceIntegration, "user@pagerduty.com"),
+				Check: resource.ComposeTestCheckFunc(
+					resource.TestCheckResourceAttr(
+						"pagerduty_service_integration.foo", "type", "generic_email_inbound_integration"),
+				),
+				PlanOnly:           true,
+				ExpectNonEmptyPlan: true,
+			},
 		},
 	})
 }
@@ -322,3 +337,51 @@ resource "pagerduty_service_integration" "foo" {
 }
 `, username, email, escalationPolicy, service, serviceIntegration)
 }
+
+func testAccCheckPagerDutyServiceIntegrationGenericEmail(username, email, escalationPolicy, service, serviceIntegration, integrationEmail string) string {
+	return fmt.Sprintf(`
+resource "pagerduty_user" "foo" {
+  name        = "%s"
+  email       = "%s"
+  color       = "green"
+  role        = "user"
+  job_title   = "foo"
+  description = "foo"
+}
+
+resource "pagerduty_escalation_policy" "foo" {
+  name        = "%s"
+  description = "bar"
+  num_loops   = 2
+
+  rule {
+    escalation_delay_in_minutes = 10
+
+    target {
+      type = "user_reference"
+      id   = pagerduty_user.foo.id
+    }
+  }
+}
+
+resource "pagerduty_service" "foo" {
+  name                    = "%s"
+  description             = "bar"
+  auto_resolve_timeout    = 3600
+  acknowledgement_timeout = 3600
+  escalation_policy       = pagerduty_escalation_policy.foo.id
+
+  incident_urgency_rule {
+    type    = "constant"
+    urgency = "high"
+  }
+}
+
+resource "pagerduty_service_integration" "foo" {
+  name              = "%s"
+  service           = pagerduty_service.foo.id
+  type              = "generic_email_inbound_integration"
+  integration_email = "%s"
+}
+`, username, email, escalationPolicy, service, serviceIntegration, integrationEmail)
+}