Add some validation around parameters being unique, and unit tests wrt that

Author: wildjames

packages/cdkConstructs/src/constructs/SsmParametersConstruct.ts

@@ -36,7 +36,7 @@ export interface SsmParametersConstructProps {
   /**
    * Prefix used in SSM parameter names and CloudFormation export names.
    */
-  readonly stackName: string
+  readonly namePrefix: string
   /**
    * List of SSM parameters to create.
    */
@@ -70,7 +70,7 @@ export class SsmParametersConstruct extends Construct {
     super(scope, id)
 
     const {
-      stackName,
+      namePrefix: stackName,
       parameters,
       readPolicyDescription = "Allows reading SSM parameters",
       readPolicyOutputDescription = "Access to the parameters used by the integration",
@@ -83,9 +83,24 @@ export class SsmParametersConstruct extends Construct {
 
     const createdParameters: Record<string, StringParameter> = {}
 
+    const seenIds = new Set<string>()
+    const seenNames = new Set<string>()
+
     for (const parameter of parameters) {
-      const ssmParameter = new StringParameter(this, `${parameter.id}Parameter`, {
-        parameterName: `${stackName}-${parameter.nameSuffix}`,
+      const parameterId = `${parameter.id}Parameter`
+      if (seenIds.has(parameterId)) {
+        throw new Error(`Duplicate parameter id detected: ${parameter.id}.`)
+      }
+      seenIds.add(parameterId)
+
+      const parameterName = `${stackName}-${parameter.nameSuffix}`
+      if (seenNames.has(parameterName)) {
+        throw new Error(`Duplicate parameter name detected: ${parameterName}.`)
+      }
+      seenNames.add(parameterName)
+
+      const ssmParameter = new StringParameter(this, parameterId, {
+        parameterName,
         description: parameter.description,
         stringValue: parameter.value
       })

packages/cdkConstructs/tests/constructs/ssmParametersConstruct.test.ts

@@ -18,7 +18,7 @@ describe("SsmParametersConstruct", () => {
     const stack = new Stack(app, "parameterStack")
 
     const params = new SsmParametersConstruct(stack, "TestingParameters", {
-      stackName: "mock-stack",
+      namePrefix: "mock-stack",
       parameters: [
         {
           id: "MockParam1",
@@ -127,3 +127,58 @@ describe("SsmParametersConstruct", () => {
     expect(descriptions).toContain("Mock read policy output description")
   })
 })
+
+describe("SsmParametersConstruct validation", () => {
+  test("throws when parameters array is empty", () => {
+    const app = new App()
+    const stack = new Stack(app, "emptyParamStack")
+    expect(() => new SsmParametersConstruct(stack, "EmptyParameters", {
+      namePrefix: "mock-stack",
+      parameters: []
+    })).toThrow("SsmParametersConstruct requires at least one parameter definition")
+  })
+
+  test("throws when duplicate parameter ids are detected", () => {
+    const app = new App()
+    const stack = new Stack(app, "duplicateIdStack")
+    expect(() => new SsmParametersConstruct(stack, "DuplicateIdParameters", {
+      namePrefix: "mock-stack",
+      parameters: [
+        {
+          id: "MockParam1",
+          nameSuffix: "MockParam1",
+          description: "Description for mock parameter 1",
+          value: "mock-value-1"
+        },
+        {
+          id: "MockParam1",
+          nameSuffix: "MockParam1Different",
+          description: "Description for duplicate id parameter",
+          value: "mock-value-2"
+        }
+      ]
+    })).toThrow("Duplicate parameter id detected: MockParam1.")
+  })
+
+  test("throws when duplicate parameter names are detected", () => {
+    const app = new App()
+    const stack = new Stack(app, "duplicateNameStack")
+    expect(() => new SsmParametersConstruct(stack, "DuplicateNameParameters", {
+      namePrefix: "mock-stack",
+      parameters: [
+        {
+          id: "MockParam1",
+          nameSuffix: "SharedSuffix",
+          description: "Description for mock parameter 1",
+          value: "mock-value-1"
+        },
+        {
+          id: "MockParam2",
+          nameSuffix: "SharedSuffix",
+          description: "Description for duplicate name parameter",
+          value: "mock-value-2"
+        }
+      ]
+    })).toThrow("Duplicate parameter name detected: mock-stack-SharedSuffix.")
+  })
+})