Add ssm_document spread lane for owned EC2 via SSM Run Command.

agent/deploy/discover_join_test.go

@@ -183,6 +183,20 @@ func TestExecuteDeployPlanDNSTXTWithMockResolver(t *testing.T) {
 	}
 }
 
+func TestExecuteDeployPlanSSMDocumentMock(t *testing.T) {
+	plan := DeployPlanBody{
+		JoinLane: "ssm_document", Action: "ssm_document",
+		SSMDocument: `{"schemaVersion":"2.2"}`,
+	}
+	msg, err := ExecuteDeployPlan(config.RuntimeConfig{}, plan)
+	if err != nil {
+		t.Fatal(err)
+	}
+	if !strings.Contains(msg, "ssm_document") {
+		t.Fatalf("msg=%q", msg)
+	}
+}
+
 func TestExecuteDeployPlanHonorsSpreadRouteHintDeferral(t *testing.T) {
 	plan := DeployPlanBody{
 		JoinLane: "spread_smb_unc",