Allow default values in env vars. Tests

Author: wildjames

packages/cdkConstructs/src/config/index.ts

@@ -2,21 +2,36 @@ import {CloudFormationClient, DescribeStacksCommand} from "@aws-sdk/client-cloud
 import {S3Client, HeadObjectCommand} from "@aws-sdk/client-s3"
 import {StandardStackProps} from "../apps/createApp"
 
-export function getConfigFromEnvVar(varName: string, prefix: string = "CDK_CONFIG_"): string {
+export function getConfigFromEnvVar(
+  varName: string,
+  prefix: string = "CDK_CONFIG_",
+  defaultValue: string | undefined = undefined
+): string {
   const value = process.env[prefix + varName]
   if (!value) {
+    if (defaultValue !== undefined) {
+      return defaultValue
+    }
     throw new Error(`Environment variable ${prefix}${varName} is not set`)
   }
   return value
 }
 
-export function getBooleanConfigFromEnvVar(varName: string, prefix: string = "CDK_CONFIG_"): boolean {
-  const value = getConfigFromEnvVar(varName, prefix)
+export function getBooleanConfigFromEnvVar(
+  varName: string,
+  prefix: string = "CDK_CONFIG_",
+  defaultValue: string | undefined = undefined
+): boolean {
+  const value = getConfigFromEnvVar(varName, prefix, defaultValue)
   return value.toLowerCase().trim() === "true"
 }
 
-export function getNumberConfigFromEnvVar(varName: string, prefix: string = "CDK_CONFIG_"): number {
-  const value = getConfigFromEnvVar(varName, prefix)
+export function getNumberConfigFromEnvVar(
+  varName: string,
+  prefix: string = "CDK_CONFIG_",
+  defaultValue: string | undefined = undefined
+): number {
+  const value = getConfigFromEnvVar(varName, prefix, defaultValue)
   return Number(value)
 }
 

packages/cdkConstructs/tests/config/index.test.ts

@@ -93,6 +93,12 @@ describe("config helpers", () => {
     expect(getConfigFromEnvVar("STACK_NAME")).toBe("primary")
   })
 
+  test("getConfigFromEnvVar returns the default value when env var is not set", () => {
+    delete process.env.CDK_CONFIG_MISSING
+
+    expect(getConfigFromEnvVar("MISSING", "CDK_CONFIG_", "fallback")).toBe("fallback")
+  })
+
   test("getConfigFromEnvVar throws when value is missing", () => {
     delete process.env.CDK_CONFIG_MISSING
 
@@ -114,12 +120,31 @@ describe("config helpers", () => {
     expect(getBooleanConfigFromEnvVar("OTHER_FLAG")).toBe(false)
   })
 
+  test("getBooleanConfigFromEnvVar uses default value when env var is not set", () => {
+    delete process.env.CDK_CONFIG_BOOL_MISSING
+
+    expect(getBooleanConfigFromEnvVar("BOOL_MISSING", "CDK_CONFIG_", "true")).toBe(true)
+    expect(getBooleanConfigFromEnvVar("BOOL_MISSING", "CDK_CONFIG_", "false")).toBe(false)
+  })
+
   test("getNumberConfigFromEnvVar parses numeric strings", () => {
     process.env.CDK_CONFIG_TIMEOUT = "45"
 
     expect(getNumberConfigFromEnvVar("TIMEOUT")).toBe(45)
   })
 
+  test("getNumberConfigFromEnvVar uses default value when env var is not set", () => {
+    delete process.env.CDK_CONFIG_NUM_MISSING
+
+    expect(getNumberConfigFromEnvVar("NUM_MISSING", "CDK_CONFIG_", "99")).toBe(99)
+  })
+
+  test("getConfigFromEnvVar ignores default value when env var is set", () => {
+    process.env.CDK_CONFIG_STACK_NAME = "primary"
+
+    expect(getConfigFromEnvVar("STACK_NAME", "CDK_CONFIG_", "ignored")).toBe("primary")
+  })
+
   test("getTrustStoreVersion returns the version ID from S3", async () => {
     mockCloudFormationSend.mockResolvedValueOnce({
       Stacks: [{

packages/deploymentUtils/src/config/index.ts

@@ -3,7 +3,7 @@ import {CloudFormationClient, ListExportsCommand} from "@aws-sdk/client-cloudfor
 export function getConfigFromEnvVar(varName: string, defaultValue: string | undefined = undefined): string {
   const value = process.env[varName]
   if (!value) {
-    if (defaultValue) {
+    if (defaultValue !== undefined) {
       return defaultValue
     }
     throw new Error(`Environment variable ${varName} is not set`)