Make steps specify required/provided subject keys

[MAILPOET-4629]

mailpoet/lib/Automation/Engine/Control/RootStep.php

@@ -17,4 +17,8 @@ class RootStep implements Step {
   public function getArgsSchema(): ObjectSchema {
     return new ObjectSchema();
   }
+
+  public function getSubjectKeys(): array {
+    return [];
+  }
 }

mailpoet/lib/Automation/Engine/Workflows/Step.php

@@ -10,4 +10,7 @@ interface Step {
   public function getName(): string;
 
   public function getArgsSchema(): ObjectSchema;
+
+  /** @return string[] */
+  public function getSubjectKeys(): array;
 }

mailpoet/lib/Automation/Integrations/Core/Actions/DelayAction.php

@@ -36,6 +36,10 @@ class DelayAction implements Action {
     ]);
   }
 
+  public function getSubjectKeys(): array {
+    return [];
+  }
+
   public function run(Workflow $workflow, WorkflowRun $workflowRun, Step $step): void {
     $nextStep = $step->getNextSteps()[0] ?? null;
     $this->actionScheduler->schedule(time() + $this->calculateSeconds($step), Hooks::WORKFLOW_STEP, [

mailpoet/lib/Automation/Integrations/MailPoet/Actions/SendEmailAction.php

@@ -72,6 +72,13 @@ class SendEmailAction implements Action {
     ]);
   }
 
+  public function getSubjectKeys(): array {
+    return [
+      'mailpoet:segment',
+      'mailpoet:subscriber',
+    ];
+  }
+
   public function isValid(array $subjects, Step $step, Workflow $workflow): bool {
     try {
       $this->getEmailForStep($step);

mailpoet/lib/Automation/Integrations/MailPoet/Triggers/SomeoneSubscribesTrigger.php

@@ -39,6 +39,13 @@ class SomeoneSubscribesTrigger implements Trigger {
     ]);
   }
 
+  public function getSubjectKeys(): array {
+    return [
+      SubscriberSubject::KEY,
+      SegmentSubject::KEY,
+    ];
+  }
+
   public function registerHooks(): void {
     $this->wp->addAction('mailpoet_segment_subscribed', [$this, 'handleSubscription'], 10, 2);
   }

mailpoet/tests/integration/Automation/Engine/Data/WorkflowRunLogTest.php

@@ -285,6 +285,11 @@ class TestAction implements Action {
     $this->callback = $callback;
   }
 
+
+  public function getSubjectKeys(): array {
+    return [];
+  }
+
   public function isValid(array $subjects, Step $step, Workflow $workflow): bool {
     return true;
   }