test to demonstrate multiple fieldpaths issue in replacements

api/filters/replacement/replacement_test.go

@@ -1338,6 +1338,84 @@ spec:
 `,
 			expectedErr: "delimiter option can only be used with scalar nodes",
 		},
+		// test to demonstrate https://github.com/kubernetes-sigs/kustomize/issues/3927
+		// the source field is overwritten when there are multiple fieldPaths
+		"multiple field paths in target": {
+			input: `apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: source
+data:
+  value: example
+---
+apiVersion: kubernetes-client.io/v1
+kind: ExternalSecret
+metadata:
+  name: some-secret
+spec:
+  backendType: secretsManager
+  data:
+    - key: some-prefix-replaceme
+      name: first
+      version: latest
+      property: first
+    - key: some-prefix-replaceme
+      name: second
+      version: latest
+      property: second
+    - key: some-prefix-replaceme
+      name: third
+      version: latest
+      property: third
+`,
+			replacements: `replacements:
+- source:
+    kind: ConfigMap
+    version: v1
+    name: source
+    fieldPath: data.value
+  targets:
+  - select:
+      group: kubernetes-client.io
+      version: v1
+      kind: ExternalSecret
+      name: some-secret
+    fieldPaths:
+    - spec.data.0.key
+    - spec.data.1.key
+    - spec.data.2.key
+    options:
+      delimiter: "-"
+      index: 2
+`,
+			expected: `apiVersion: v1
+kind: ConfigMap
+metadata:
+  name: source
+data:
+  value: some-prefix-some-prefix-some-prefix-example
+---
+apiVersion: kubernetes-client.io/v1
+kind: ExternalSecret
+metadata:
+  name: some-secret
+spec:
+  backendType: secretsManager
+  data:
+  - key: some-prefix-example
+    name: first
+    version: latest
+    property: first
+  - key: some-prefix-some-prefix-example
+    name: second
+    version: latest
+    property: second
+  - key: some-prefix-some-prefix-some-prefix-example
+    name: third
+    version: latest
+    property: third
+`,
+		},
 	}
 
 	for tn, tc := range testCases {