From 00c64dbf357bfee235244168a311174273295bb5 Mon Sep 17 00:00:00 2001
From: Tom Wieczorek <twieczorek@mirantis.com>
Date: Wed, 2 Oct 2024 16:03:30 +0200
Subject: [PATCH] Add some simpe tests for the applier manager

Signed-off-by: Tom Wieczorek <twieczorek@mirantis.com>
---
 internal/testutil/fakeclient/tracker.go | 12 +++
 pkg/applier/manager_test.go             | 98 +++++++++++++++++++++++++
 2 files changed, 110 insertions(+)
 create mode 100644 pkg/applier/manager_test.go

diff --git a/internal/testutil/fakeclient/tracker.go b/internal/testutil/fakeclient/tracker.go
index c319e089cd42..5fe762e3d80b 100644
--- a/internal/testutil/fakeclient/tracker.go
+++ b/internal/testutil/fakeclient/tracker.go
@@ -20,6 +20,8 @@ import (
 	"fmt"
 	"net/http"
 	"reflect"
+	"strconv"
+	"time"
 	"unsafe"
 
 	"k8s.io/apimachinery/pkg/api/meta"
@@ -128,6 +130,16 @@ func (t *TransformingObjectTracker) List(gvr schema.GroupVersionResource, gvk sc
 		return obj, fmt.Errorf("failed to externalize object: %w", err)
 	}
 
+	// Set a fake resource version, so that watches work.
+	if external, ok := external.(interface {
+		GetResourceVersion() string
+		SetResourceVersion(string)
+	}); ok {
+		if external.GetResourceVersion() == "" {
+			external.SetResourceVersion(strconv.FormatInt(time.Now().UnixMilli(), 10))
+		}
+	}
+
 	return external, nil
 }
 
diff --git a/pkg/applier/manager_test.go b/pkg/applier/manager_test.go
new file mode 100644
index 000000000000..1df8dd8ec25d
--- /dev/null
+++ b/pkg/applier/manager_test.go
@@ -0,0 +1,98 @@
+/*
+Copyright 2024 k0s authors
+
+Licensed under the Apache License, Version 2.0 (the "License");
+you may not use this file except in compliance with the License.
+You may obtain a copy of the License at
+
+    http://www.apache.org/licenses/LICENSE-2.0
+
+Unless required by applicable law or agreed to in writing, software
+distributed under the License is distributed on an "AS IS" BASIS,
+WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+See the License for the specific language governing permissions and
+limitations under the License.
+*/
+
+package applier_test
+
+import (
+	"context"
+	"os"
+	"path/filepath"
+	"testing"
+
+	"github.com/k0sproject/k0s/internal/testutil"
+	"github.com/k0sproject/k0s/pkg/applier"
+	"github.com/k0sproject/k0s/pkg/component/controller/leaderelector"
+	"github.com/k0sproject/k0s/pkg/config"
+	"github.com/k0sproject/k0s/pkg/constant"
+	"github.com/k0sproject/k0s/pkg/kubernetes/watch"
+
+	corev1 "k8s.io/api/core/v1"
+
+	"github.com/stretchr/testify/assert"
+	"github.com/stretchr/testify/require"
+)
+
+func TestManager_AppliesStacks(t *testing.T) {
+	k0sVars, err := config.NewCfgVars(nil, t.TempDir())
+	require.NoError(t, err)
+	leaderElector := leaderelector.Dummy{Leader: true}
+	clients := testutil.NewFakeClientFactory()
+
+	underTest := applier.Manager{
+		K0sVars:           k0sVars,
+		KubeClientFactory: clients,
+		LeaderElector:     &leaderElector,
+	}
+
+	// A stack that exists on disk before the manager is started.
+	before := filepath.Join(k0sVars.ManifestsDir, "before")
+	require.NoError(t, os.MkdirAll(before, constant.ManifestsDirMode))
+	os.WriteFile(filepath.Join(before, "before.yaml"), []byte(`
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: before
+  namespace: default
+  resourceVersion: "1"
+data: {}
+`,
+	), constant.CertMode)
+
+	require.NoError(t, leaderElector.Init(context.TODO()))
+	require.NoError(t, underTest.Init(context.TODO()))
+	require.NoError(t, underTest.Start(context.TODO()))
+	t.Cleanup(func() { assert.NoError(t, underTest.Stop()) })
+	require.NoError(t, leaderElector.Start(context.TODO()))
+	t.Cleanup(func() { assert.NoError(t, leaderElector.Stop()) })
+
+	// Wait for the "before" stack to be applied.
+	require.NoError(t, watch.ConfigMaps(clients.Client.CoreV1().ConfigMaps("default")).
+		Until(context.TODO(), func(item *corev1.ConfigMap) (bool, error) {
+			return item.Name == "before", nil
+		}),
+	)
+
+	// A stack that is created on disk after the manager has started.
+	after := filepath.Join(k0sVars.ManifestsDir, "after")
+	require.NoError(t, os.MkdirAll(after, constant.ManifestsDirMode))
+	os.WriteFile(filepath.Join(after, "after.yaml"), []byte(`
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: after
+  namespace: default
+  resourceVersion: "1"
+data: {}
+`,
+	), constant.CertMode)
+
+	// Wait for the "after" stack to be applied.
+	require.NoError(t, watch.ConfigMaps(clients.Client.CoreV1().ConfigMaps("default")).
+		Until(context.TODO(), func(item *corev1.ConfigMap) (bool, error) {
+			return item.Name == "after", nil
+		}),
+	)
+}