From b7d19b63ac15c6e956f58da9fdd97b9bb595ca70 Mon Sep 17 00:00:00 2001
From: Daniel Franz <dfranz@redhat.com>
Date: Mon, 27 Apr 2026 13:10:24 +0900
Subject: [PATCH] Concurrent Test Execution

Takes advantage of changes made to isolate test runs to execute as many tests in parallel as possible. For tests that must be run serially, the @Serial tag has been added to the beginning of relevant feature file(s).

Signed-off-by: Daniel Franz <dfranz@redhat.com>
Co-authored-by: Claude Sonnet 4.5 <noreply@anthropic.com>
---
 Makefile                        | 13 ++++++++++++-
 test/e2e/README.md              | 32 ++++++++++++++++++++++++++++++++
 test/e2e/features/ha.feature    |  1 +
 test/e2e/features/proxy.feature |  1 +
 test/e2e/features/tls.feature   |  1 +
 5 files changed, 47 insertions(+), 1 deletion(-)

diff --git a/Makefile b/Makefile
index a22f9a03a..80ca60164 100644
--- a/Makefile
+++ b/Makefile
@@ -258,7 +258,18 @@ E2E_TIMEOUT ?= 20m
 GODOG_ARGS ?=
 .PHONY: e2e
 e2e: #EXHELP Run the e2e tests.
-	go test -count=1 -v ./test/e2e/features_test.go -timeout=$(E2E_TIMEOUT) $(if $(GODOG_ARGS),-args $(GODOG_ARGS))
+ifeq ($(strip $(GODOG_ARGS)),)
+	go test -count=1 -v ./test/e2e/features_test.go -timeout=$(E2E_TIMEOUT) -args --godog.tags="~@Serial" --godog.concurrency=100; \
+	parallelExitCode=$$?; \
+	go test -count=1 -v ./test/e2e/features_test.go -timeout=$(E2E_TIMEOUT) -args --godog.tags="@Serial" --godog.concurrency=1; \
+	serialExitCode=$$?; \
+	if [ $$parallelExitCode -ne 0 ] || [ $$serialExitCode -ne 0 ]; then \
+		echo "e2e tests failed: parallel=$$parallelExitCode serial=$$serialExitCode"; \
+		exit 1; \
+	fi
+else
+	go test -count=1 -v ./test/e2e/features_test.go -timeout=$(E2E_TIMEOUT) -args $(GODOG_ARGS)
+endif
 
 export CLUSTER_REGISTRY_HOST := docker-registry.operator-controller-e2e.svc:5000
 .PHONY: extension-developer-e2e
diff --git a/test/e2e/README.md b/test/e2e/README.md
index 98b99b9ca..3aa276f8a 100644
--- a/test/e2e/README.md
+++ b/test/e2e/README.md
@@ -207,6 +207,10 @@ Use these variables in YAML templates:
 
 ### 5. Feature Tags
 
+Tags can be used for different purposes in the test suite:
+
+#### Feature Gate Tags
+
 Use tags to conditionally run scenarios based on feature gates:
 
 ```gherkin
@@ -216,6 +220,28 @@ Scenario: Install operator having webhooks
 
 Scenarios are skipped if the feature gate is not enabled on the deployed controller.
 
+#### Serial Execution Tag
+
+By default, scenarios run concurrently (up to 100 parallel scenarios). However, some tests must run serially, typically because they:
+- Modify shared cluster resources (e.g., cluster-wide TLS configuration)
+- Have resource constraints that prevent parallel execution
+- Require exclusive access to a resource
+
+To mark a test for serial execution, add the `@Serial` tag:
+
+```gherkin
+@Serial
+Feature: TLS profile enforcement on metrics endpoints
+
+  Scenario: Test TLS configuration
+    Given the "catalogd" deployment is configured with custom TLS settings
+    ...
+```
+
+The test runner automatically separates scenarios:
+- Scenarios **without** `@Serial` run concurrently in the first test phase
+- Scenarios **with** `@Serial` run sequentially in a separate serial test phase
+
 ## Running Tests
 
 ### Run All Tests
@@ -243,6 +269,12 @@ go test test/e2e/features_test.go -- features/install.feature
 go test test/e2e/features_test.go --godog.tags="@WebhookProviderCertManager"
 ```
 
+Note that setting the tags in this way will disable the automatic test parallelization. If running in parallel with custom tags is desired, set `--godog.concurrency=100` for instance to re-enable. If this is done adding `&& ~@Serial` to the tags as well is highly recommended:
+
+```bash
+go test test/e2e/features_test.go --godog.tags="@WebhookProviderCertManager && ~@Serial" --godog.concurrency=100
+```
+
 ### Run with Debug Logging
 
 ```bash
diff --git a/test/e2e/features/ha.feature b/test/e2e/features/ha.feature
index 6b889c99b..bb20cfafa 100644
--- a/test/e2e/features/ha.feature
+++ b/test/e2e/features/ha.feature
@@ -1,3 +1,4 @@
+@Serial
 Feature: HA failover for catalogd
 
   When catalogd is deployed with multiple replicas, the remaining pods must
diff --git a/test/e2e/features/proxy.feature b/test/e2e/features/proxy.feature
index c4ddcc091..9f30a47f0 100644
--- a/test/e2e/features/proxy.feature
+++ b/test/e2e/features/proxy.feature
@@ -1,3 +1,4 @@
+@Serial
 Feature: HTTPS proxy support for outbound catalog requests
 
   OLM's operator-controller fetches catalog data from catalogd over HTTPS.
diff --git a/test/e2e/features/tls.feature b/test/e2e/features/tls.feature
index 77293c12f..c13079633 100644
--- a/test/e2e/features/tls.feature
+++ b/test/e2e/features/tls.feature
@@ -1,3 +1,4 @@
+@Serial
 Feature: TLS profile enforcement on metrics endpoints
 
   Background: