diff --git a/api/krusty/mergeenvfrom_test.go b/api/krusty/mergeenvfrom_test.go
new file mode 100644
index 000000000..b1213c2e1
--- /dev/null
+++ b/api/krusty/mergeenvfrom_test.go
@@ -0,0 +1,110 @@
+// Copyright 2019 The Kubernetes Authors.
+// SPDX-License-Identifier: Apache-2.0
+
+package krusty_test
+
+import (
+	"testing"
+
+	kusttest_test "sigs.k8s.io/kustomize/api/testutils/kusttest"
+)
+
+func makeCommonFileForMergeEnvFromTest(th kusttest_test.Harness) {
+	th.WriteF("/app/deployment.yaml", `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx
+spec:
+  template:
+    spec:
+      containers:
+      - name: nginx
+        image: image1
+        envFrom:
+        - configMapRef:
+            name: some-config
+        - configMapRef:
+            name: more-config
+`)
+}
+
+// When patching, `envFrom` should merge the list instead of replacing it.
+func TestMergeEnvFrom(t *testing.T) {
+	th := kusttest_test.MakeHarness(t)
+	makeCommonFileForMergeEnvFromTest(th)
+	th.WriteK("/app", `
+resources:
+- deployment.yaml
+
+patchesStrategicMerge:
+- |-
+  apiVersion: apps/v1
+  kind: Deployment
+  metadata:
+    name: nginx
+  spec:
+    template:
+      spec:
+        containers:
+        - name: nginx
+          envFrom:
+          - configMapRef:
+              name: another-config
+`)
+	m := th.Run("/app", th.MakeDefaultOptions())
+	th.AssertActualEqualsExpected(m, `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx
+spec:
+  template:
+    spec:
+      containers:
+      - envFrom:
+        - configMapRef:
+            name: another-config
+        image: image1
+        name: nginx
+`)
+}
+
+func TestMergeEnvFromViaJsonInline(t *testing.T) {
+	th := kusttest_test.MakeHarness(t)
+	makeCommonFileForMergeEnvFromTest(th)
+	th.WriteK("app", `
+resources:
+- deployment.yaml
+patches:
+- target:
+    kind: Deployment
+    name: nginx
+  patch: |-
+    - op: add
+      path: /spec/template/spec/containers/0/envFrom/-
+      value:
+        configMapRef:
+          name: another-config
+`)
+	m := th.Run("app", th.MakeDefaultOptions())
+	th.AssertActualEqualsExpected(m, `
+apiVersion: apps/v1
+kind: Deployment
+metadata:
+  name: nginx
+spec:
+  template:
+    spec:
+      containers:
+      - envFrom:
+        - configMapRef:
+            name: some-config
+        - configMapRef:
+            name: more-config
+        - configMapRef:
+            name: another-config
+        image: image1
+        name: nginx
+`)
+}