Test feature flag endpoint in CI (#512)

* Hit feature-flags endpoint in example app during CI Infra service tests
* Hit feature-flags endpoint in example app during Template only CI Infra tests

## Context

[This
commit](8bfab43)
broke the feature flag evidently integration (fixed now) but it was not
caught as part of any automated testing. This change adds a ping to the
feature-flags endpoint which integrates with Evidently to catch future
regressions.

infra/test/infra_test.go

@@ -99,6 +99,11 @@ func RunEndToEndTests(t *testing.T, terraformOptions *terraform.Options) {
 	http_helper.HttpGetWithRetryWithCustomValidation(t, serviceEndpoint, nil, 5, 1*time.Second, func(responseStatus int, responseBody string) bool {
 		return responseStatus == 200
 	})
+	// Hit feature flags endpoint to make sure Evidently integration is working
+	featureFlagsEndpoint := fmt.Sprintf("%s/feature-flags", serviceEndpoint)
+	http_helper.HttpGetWithRetryWithCustomValidation(t, featureFlagsEndpoint, nil, 5, 1*time.Second, func(responseStatus int, responseBody string) bool {
+		return responseStatus == 200
+	})
 	fmt.Println("::endgroup::")
 }
 

template-only-test/template_infra_test.go

@@ -197,6 +197,13 @@ func ValidateDevEnvironment(t *testing.T) {
 	http_helper.HttpGetWithRetryWithCustomValidation(t, serviceEndpoint, nil, 10, 3*time.Second, func(responseStatus int, responseBody string) bool {
 		return responseStatus == 200
 	})
+
+	// Hit feature flags endpoint to make sure Evidently integration is working
+	featureFlagsEndpoint := fmt.Sprintf("%s/feature-flags", serviceEndpoint)
+	http_helper.HttpGetWithRetryWithCustomValidation(t, featureFlagsEndpoint, nil, 10, 3*time.Second, func(responseStatus int, responseBody string) bool {
+		return responseStatus == 200
+	})
+
 	fmt.Println("::endgroup::")
 }