diff --git a/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/configmap.yaml b/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/configmap.yaml
new file mode 100644
index 00000000..078b4c15
--- /dev/null
+++ b/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/configmap.yaml
@@ -0,0 +1,7 @@
+apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: app-config
+  namespace: new-ns
+data:
+  key: value
diff --git a/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/kustomization.yaml b/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/kustomization.yaml
new file mode 100644
index 00000000..491d68b1
--- /dev/null
+++ b/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/kustomization.yaml
@@ -0,0 +1,5 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- ./namespace.yaml
+- ./configmap.yaml
diff --git a/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/namespace.yaml b/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/namespace.yaml
new file mode 100644
index 00000000..4755a448
--- /dev/null
+++ b/cmd/flux/testdata/build-kustomization/new-namespace-and-configmap/namespace.yaml
@@ -0,0 +1,4 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: new-ns
diff --git a/cmd/flux/testdata/build-kustomization/new-namespace-only/kustomization.yaml b/cmd/flux/testdata/build-kustomization/new-namespace-only/kustomization.yaml
new file mode 100644
index 00000000..73029636
--- /dev/null
+++ b/cmd/flux/testdata/build-kustomization/new-namespace-only/kustomization.yaml
@@ -0,0 +1,4 @@
+apiVersion: kustomize.config.k8s.io/v1beta1
+kind: Kustomization
+resources:
+- ./namespace.yaml
diff --git a/cmd/flux/testdata/build-kustomization/new-namespace-only/namespace.yaml b/cmd/flux/testdata/build-kustomization/new-namespace-only/namespace.yaml
new file mode 100644
index 00000000..4755a448
--- /dev/null
+++ b/cmd/flux/testdata/build-kustomization/new-namespace-only/namespace.yaml
@@ -0,0 +1,4 @@
+apiVersion: v1
+kind: Namespace
+metadata:
+  name: new-ns
diff --git a/cmd/flux/testdata/diff-kustomization/diff-new-namespace-only.golden b/cmd/flux/testdata/diff-kustomization/diff-new-namespace-only.golden
new file mode 100644
index 00000000..77493d65
--- /dev/null
+++ b/cmd/flux/testdata/diff-kustomization/diff-new-namespace-only.golden
@@ -0,0 +1 @@
+► Namespace/new-ns created
diff --git a/cmd/flux/testdata/diff-kustomization/flux-kustomization-new-namespace-and-configmap.yaml b/cmd/flux/testdata/diff-kustomization/flux-kustomization-new-namespace-and-configmap.yaml
new file mode 100644
index 00000000..e045b495
--- /dev/null
+++ b/cmd/flux/testdata/diff-kustomization/flux-kustomization-new-namespace-and-configmap.yaml
@@ -0,0 +1,13 @@
+---
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: new-namespace-and-configmap
+spec:
+  interval: 5m0s
+  path: ./kustomize
+  force: true
+  prune: true
+  sourceRef:
+    kind: GitRepository
+    name: new-namespace-and-configmap
diff --git a/cmd/flux/testdata/diff-kustomization/flux-kustomization-new-namespace-only.yaml b/cmd/flux/testdata/diff-kustomization/flux-kustomization-new-namespace-only.yaml
new file mode 100644
index 00000000..56401cf8
--- /dev/null
+++ b/cmd/flux/testdata/diff-kustomization/flux-kustomization-new-namespace-only.yaml
@@ -0,0 +1,13 @@
+---
+apiVersion: kustomize.toolkit.fluxcd.io/v1
+kind: Kustomization
+metadata:
+  name: new-namespace-only
+spec:
+  interval: 5m0s
+  path: ./kustomize
+  force: true
+  prune: true
+  sourceRef:
+    kind: GitRepository
+    name: new-namespace-only