feat: add noDuplicates pipe function for duplicate data verification (#145)

Author: wu-sheng

docs/en/setup/Configuration-File.md

@@ -248,6 +248,19 @@ For example, if a generic expected entry (e.g., `notEmpty`) appears before a spe
 {{- end }}
 ```
 
+##### Duplicate Detection
+
+`noDuplicates` is a pipe function that verifies a list contains no duplicate items. Two items are considered duplicates when all their fields are equal. It can be combined with `contains`, `containsOnce`, or `range`.
+
+```yaml
+{{- contains (.metrics | noDuplicates) }}
+- name: {{ notEmpty .name }}
+  value: {{ notEmpty .value }}
+{{- end }}
+```
+
+When duplicates exist in the actual data, verification will fail with an error indicating the duplicated item.
+
 ##### Encoding
 
 In order to make the program easier for users to read and use, some code conversions are provided.

internal/components/verifier/funcs.go

@@ -54,6 +54,9 @@ var customFuncMap = map[string]any{
 
 	// Calculation:
 	"subtractor": subtractor,
+
+	// List:
+	"noDuplicates": noDuplicates,
 }
 
 func base64encode(s string) string {
@@ -103,3 +106,18 @@ func subtractor(total int, nums ...int) int {
 	}
 	return total
 }
+
+func noDuplicates(list any) any {
+	items, ok := list.([]any)
+	if !ok {
+		return list
+	}
+	for i := 0; i < len(items); i++ {
+		for j := i + 1; j < len(items); j++ {
+			if fmt.Sprint(items[i]) == fmt.Sprint(items[j]) {
+				return fmt.Sprintf("<duplicate found: %v>", items[i])
+			}
+		}
+	}
+	return list
+}

internal/components/verifier/verifier_test.go

@@ -501,6 +501,83 @@ metrics:
 			},
 			wantErr: true, // service-A does not exist in actual
 		},
+		{
+			name: "noDuplicates should pass when list has no duplicates",
+			args: args{
+				actualData: `
+metrics:
+  - name: service-A
+    value: "100"
+  - name: service-B
+    value: "200"
+`,
+				expectedTemplate: `
+metrics:
+{{- contains (.metrics | noDuplicates) }}
+  - name: {{ notEmpty .name }}
+    value: {{ notEmpty .value }}
+{{- end }}
+`,
+			},
+			wantErr: false,
+		},
+		{
+			name: "noDuplicates should fail when list has duplicate items",
+			args: args{
+				actualData: `
+metrics:
+  - name: service-A
+    value: "100"
+  - name: service-A
+    value: "100"
+`,
+				expectedTemplate: `
+metrics:
+{{- contains (.metrics | noDuplicates) }}
+  - name: {{ notEmpty .name }}
+    value: {{ notEmpty .value }}
+{{- end }}
+`,
+			},
+			wantErr: true, // duplicate entry exists
+		},
+		{
+			name: "noDuplicates should work with containsOnce",
+			args: args{
+				actualData: `
+- name: service-A
+  value: "100"
+- name: service-B
+  value: "200"
+- name: service-A
+  value: "100"
+`,
+				expectedTemplate: `
+{{- containsOnce (. | noDuplicates) }}
+- name: {{ notEmpty .name }}
+  value: {{ notEmpty .value }}
+{{- end }}
+`,
+			},
+			wantErr: true, // duplicate entry exists even though containsOnce would pass
+		},
+		{
+			name: "noDuplicates should pass with range and no duplicates",
+			args: args{
+				actualData: `
+metrics:
+  - name: service-A
+  - name: service-B
+`,
+				expectedTemplate: `
+metrics:
+{{- range (.metrics | noDuplicates) }}
+  - name: {{ notEmpty .name }}
+{{- end }}
+`,
+			},
+			wantErr: false,
+		},
 		{
 			name: "notEmpty with nil",
 			args: args{