NomicFoundation · zoeyTM · May 6, 2025 · Apr 23, 2025 · Apr 23, 2025 · May 6, 2025
diff --git a/.changeset/twenty-pillows-switch.md b/.changeset/twenty-pillows-switch.md
@@ -0,0 +1,9 @@
+---
+"@nomicfoundation/example-project": patch
+"@nomicfoundation/hardhat-ignition": patch
+"@nomicfoundation/hardhat-mocha": patch
+"@nomicfoundation/hardhat-node-test-runner": patch
+"hardhat": patch
+---
+
+Allow undefined for default values in global options and other argument types ([#6596](https://github.com/NomicFoundation/hardhat/issues/6596)
diff --git a/v-next/example-project/hardhat.config.ts b/v-next/example-project/hardhat.config.ts
@@ -13,6 +13,7 @@ import hardhatEthersPlugin from "@nomicfoundation/hardhat-ethers";
 import hardhatChaiMatchersPlugin from "@nomicfoundation/hardhat-ethers-chai-matchers";
 import hardhatTypechain from "@nomicfoundation/hardhat-typechain";
 import hardhatIgnitionViem from "@nomicfoundation/hardhat-ignition-viem";
+import { ArgumentType } from "hardhat/types/arguments";
 
 util.inspect.defaultOptions.depth = null;
 
@@ -50,7 +51,8 @@ const exampleTaskOverride = task("example2")
   .addOption({
     name: "grep",
     description: "Only run tests matching the given string or regexp",
-    defaultValue: "",
+    type: ArgumentType.STRING_WITHOUT_DEFAULT,
+    defaultValue: undefined,
   })
   .build();
 

diff --git a/v-next/hardhat-ignition/src/index.ts b/v-next/hardhat-ignition/src/index.ts
@@ -26,22 +26,22 @@ const hardhatIgnitionPlugin: HardhatPlugin = {
       })
       .addOption({
         name: "parameters",
-        type: ArgumentType.FILE,
+        type: ArgumentType.FILE_WITHOUT_DEFAULT,
         description:
           "A relative path to a JSON file to use for the module parameters",
-        defaultValue: "", // TODO: HH3 check this comes through correctly
+        defaultValue: undefined,
       })
       .addOption({
         name: "deploymentId",
-        type: ArgumentType.STRING,
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
         description: "Set the id of the deployment",
-        defaultValue: "", // TODO: HH3 check this comes through correctly
+        defaultValue: undefined,
       })
       .addOption({
         name: "defaultSender",
-        type: ArgumentType.STRING,
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
         description: "Set the default sender for the deployment",
-        defaultValue: "", // TODO: HH3 check this comes through correctly
+        defaultValue: undefined,
       })
       .addOption({
         name: "strategy",

diff --git a/v-next/hardhat-ignition/src/internal/tasks/deploy.ts b/v-next/hardhat-ignition/src/internal/tasks/deploy.ts
@@ -177,8 +177,7 @@ const taskDeploy: NewTaskActionFunction<TaskDeployArguments> = async (
   }
 
   let parameters: DeploymentParameters | undefined;
-  // TODO: HH3 Remove the use of "" as a default value
-  if (parametersInput === undefined || parametersInput === "") {
+  if (parametersInput === undefined) {
     parameters = await resolveParametersFromModuleName(
       userModule.id,
       hre.config.paths.ignition,

diff --git a/v-next/hardhat-mocha/src/index.ts b/v-next/hardhat-mocha/src/index.ts
@@ -1,6 +1,7 @@
 import type { HardhatPlugin } from "hardhat/types/plugins";
 
 import { task } from "hardhat/config";
+import { ArgumentType } from "hardhat/types/arguments";
 
 import "./type-extensions.js";
 
@@ -20,7 +21,8 @@ const hardhatPlugin: HardhatPlugin = {
       .addOption({
         name: "grep",
         description: "Only run tests matching the given string or regexp",
-        defaultValue: "",
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
+        defaultValue: undefined,
       })
       .addFlag({
         name: "noCompile",

diff --git a/v-next/hardhat-node-test-runner/src/index.ts b/v-next/hardhat-node-test-runner/src/index.ts
@@ -1,6 +1,7 @@
 import type { HardhatPlugin } from "hardhat/types/plugins";
 
 import { task } from "hardhat/config";
+import { ArgumentType } from "hardhat/types/arguments";
 
 import "./type-extensions.js";
 
@@ -20,7 +21,8 @@ const hardhatPlugin: HardhatPlugin = {
       .addOption({
         name: "grep",
         description: "Only run tests matching the given string or regexp",
-        defaultValue: "",
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
+        defaultValue: undefined,
       })
       .addFlag({
         name: "noCompile",

diff --git a/v-next/hardhat/src/internal/builtin-global-options.ts b/v-next/hardhat/src/internal/builtin-global-options.ts
@@ -12,8 +12,8 @@ export const BUILTIN_GLOBAL_OPTIONS_DEFINITIONS: GlobalOptionDefinitions =
         option: globalOption({
           name: "config",
           description: "A Hardhat config file.",
-          type: ArgumentType.STRING,
-          defaultValue: "",
+          type: ArgumentType.STRING_WITHOUT_DEFAULT,
+          defaultValue: undefined,
         }),
       },
     ],

diff --git a/v-next/hardhat/src/internal/builtin-plugins/network-manager/hook-handlers/hre.ts b/v-next/hardhat/src/internal/builtin-plugins/network-manager/hook-handlers/hre.ts
@@ -15,7 +15,7 @@ export default async (): Promise<Partial<HardhatRuntimeEnvironmentHooks>> => ({
 
         if (networkManager === undefined) {
           networkManager = new NetworkManagerImplementation(
-            hre.globalOptions.network !== ""
+            hre.globalOptions.network !== undefined
               ? hre.globalOptions.network
               : hre.config.defaultNetwork,
             hre.config.defaultChainType,

diff --git a/v-next/hardhat/src/internal/builtin-plugins/network-manager/index.ts b/v-next/hardhat/src/internal/builtin-plugins/network-manager/index.ts
@@ -1,5 +1,6 @@
 import type { HardhatPlugin } from "../../../types/plugins.js";
 
+import { ArgumentType } from "../../../types/arguments.js";
 import { globalOption } from "../../core/config.js";
 
 import "./type-extensions/config.js";
@@ -18,7 +19,8 @@ const hardhatPlugin: HardhatPlugin = {
     globalOption({
       name: "network",
       description: "The network to connect to",
-      defaultValue: "",
+      type: ArgumentType.STRING_WITHOUT_DEFAULT,
+      defaultValue: undefined,
     }),
   ],
   npmPackage: "hardhat",

diff --git a/v-next/hardhat/src/internal/builtin-plugins/node/index.ts b/v-next/hardhat/src/internal/builtin-plugins/node/index.ts
@@ -11,7 +11,8 @@ const hardhatPlugin: HardhatPlugin = {
         name: "hostname",
         description:
           "The host to which to bind to for new connections (Defaults to 127.0.0.1 running locally, and 0.0.0.0 in Docker)",
-        defaultValue: "",
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
+        defaultValue: undefined,
       })
       .addOption({
         name: "port",
@@ -23,7 +24,8 @@ const hardhatPlugin: HardhatPlugin = {
         name: "chainType",
         description:
           "The chain type to connect to. If not specified, the default chain type will be used.",
-        defaultValue: "",
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
+        defaultValue: undefined,
       })
       .addOption({
         name: "chainId",
@@ -35,7 +37,8 @@ const hardhatPlugin: HardhatPlugin = {
       .addOption({
         name: "fork",
         description: "The URL of the JSON-RPC server to fork from",
-        defaultValue: "",
+        type: ArgumentType.STRING_WITHOUT_DEFAULT,
+        defaultValue: undefined,
       })
       .addOption({
         name: "forkBlockNumber",

diff --git a/v-next/hardhat/src/internal/builtin-plugins/node/task-action.ts b/v-next/hardhat/src/internal/builtin-plugins/node/task-action.ts
@@ -27,7 +27,7 @@ const nodeAction: NewTaskActionFunction<NodeActionArguments> = async (
   hre,
 ) => {
   const network =
-    hre.globalOptions.network !== ""
+    hre.globalOptions.network !== undefined
       ? hre.globalOptions.network
       : hre.config.defaultNetwork;
 
@@ -49,7 +49,7 @@ const nodeAction: NewTaskActionFunction<NodeActionArguments> = async (
   // as much as needed.
   const networkConfigOverride: EdrNetworkConfigOverride = {};
 
-  if (args.chainType !== "") {
+  if (args.chainType !== undefined) {
     if (!isEdrSupportedChainType(args.chainType)) {
       // NOTE: We could make the error more specific here.
       throw new HardhatError(
@@ -69,7 +69,7 @@ const nodeAction: NewTaskActionFunction<NodeActionArguments> = async (
   }
 
   // NOTE: --fork-block-number is only valid if --fork is specified
-  if (args.fork !== "") {
+  if (args.fork !== undefined) {
     networkConfigOverride.forking = {
       enabled: true,
       url: args.fork,
@@ -104,7 +104,7 @@ const nodeAction: NewTaskActionFunction<NodeActionArguments> = async (
   // the default hostname is "127.0.0.1" unless we are inside a docker
   // container, in that case we use "0.0.0.0"
   let hostname = args.hostname;
-  if (hostname === "") {
+  if (hostname === undefined) {
     const insideDocker = await exists("/.dockerenv");
     if (insideDocker) {
       hostname = "0.0.0.0";

diff --git a/v-next/hardhat/src/internal/cli/help/utils.ts b/v-next/hardhat/src/internal/cli/help/utils.ts
@@ -109,13 +109,30 @@ export function getSection(
   return `\n${title}:\n\n${items
     .sort((a, b) => a.name.localeCompare(b.name))
     .map(({ name, description, defaultValue }) => {
-      const defaultValueStr =
-        defaultValue !== undefined ? ` (default: ${defaultValue})` : "";
+      const defaultValueStr = getDefaultValueString(defaultValue);
       return `  ${name.padEnd(namePadding)}${description}${defaultValueStr}`;
     })
     .join("\n")}\n`;
 }
 
+function getDefaultValueString(
+  defaultValue: ArgumentTypeToValueType<ArgumentType>,
+): string {
+  if (Array.isArray(defaultValue)) {
+    if (defaultValue.length === 0) {
+      return "";
+    } else {
+      return ` (default: ${JSON.stringify(defaultValue)})`;
+    }
+  }
+
+  if (defaultValue === undefined) {
+    return "";
+  }
+
+  return ` (default: ${defaultValue})`;
+}
+
 export function getUsageString(
   task: Task,
   options: ReturnType<typeof parseOptions>["options"],

diff --git a/v-next/hardhat/src/internal/core/arguments.ts b/v-next/hardhat/src/internal/core/arguments.ts
@@ -106,6 +106,10 @@ const argumentTypeValidators: Record<
   [ArgumentType.BIGINT]: (value): value is bigint => typeof value === "bigint",
   [ArgumentType.FLOAT]: (value): value is number => typeof value === "number",
   [ArgumentType.FILE]: (value): value is string => typeof value === "string",
+  [ArgumentType.STRING_WITHOUT_DEFAULT]: (value): value is string | undefined =>
+    typeof value === "string" || value === undefined,
+  [ArgumentType.FILE_WITHOUT_DEFAULT]: (value): value is string | undefined =>
+    typeof value === "string" || value === undefined,
 };
 
 /**
@@ -121,6 +125,8 @@ export function parseArgumentValue(
   name: string,
 ): ArgumentValue {
   switch (type) {
+    case ArgumentType.STRING_WITHOUT_DEFAULT:
+    case ArgumentType.FILE_WITHOUT_DEFAULT:
     case ArgumentType.STRING:
     case ArgumentType.FILE:
       return value;

diff --git a/v-next/hardhat/src/internal/core/config-validation.ts b/v-next/hardhat/src/internal/core/config-validation.ts
@@ -375,7 +375,11 @@ export function validateOptions(
       });
     }
 
-    if (option.defaultValue === undefined) {
+    if (
+      option.type !== ArgumentType.STRING_WITHOUT_DEFAULT &&
+      option.type !== ArgumentType.FILE_WITHOUT_DEFAULT &&
+      option.defaultValue === undefined
+    ) {
       validationErrors.push({
         path: [...path, name, "defaultValue"],
         message: "option defaultValue must be defined",
@@ -392,6 +396,19 @@ export function validateOptions(
           }
           break;
         }
+        case ArgumentType.FILE_WITHOUT_DEFAULT:
+        case ArgumentType.STRING_WITHOUT_DEFAULT: {
+          if (
+            typeof option.defaultValue !== "string" &&
+            option.defaultValue !== undefined
+          ) {
+            validationErrors.push({
+              path: [...path, name, "defaultValue"],
+              message: "option defaultValue must be a string or undefined",
+            });
+          }
+          break;
+        }
         case ArgumentType.BOOLEAN: {
           if (typeof option.defaultValue !== "boolean") {
             validationErrors.push({
@@ -457,6 +474,8 @@ export function validatePositionalArguments(
 
     if (arg.defaultValue !== undefined) {
       switch (arg.type) {
+        case ArgumentType.STRING_WITHOUT_DEFAULT:
+        case ArgumentType.FILE_WITHOUT_DEFAULT:
         case ArgumentType.STRING:
         case ArgumentType.FILE: {
           if (

diff --git a/v-next/hardhat/src/internal/core/global-options.ts b/v-next/hardhat/src/internal/core/global-options.ts
@@ -69,7 +69,9 @@ export function buildGlobalOptionDefinitions(
  * Builds a global option definition, validating the name, type, and default
  * value.
  */
-export function buildGlobalOptionDefinition<T extends ArgumentType>({
+export function buildGlobalOptionDefinition<
+  T extends ArgumentType = ArgumentType.STRING,
+>({
   name,
   description,
   type,

diff --git a/v-next/hardhat/src/types/arguments.ts b/v-next/hardhat/src/types/arguments.ts
@@ -8,6 +8,8 @@ export enum ArgumentType {
   BIGINT = "BIGINT",
   FLOAT = "FLOAT",
   FILE = "FILE",
+  STRING_WITHOUT_DEFAULT = "STRING_WITHOUT_DEFAULT",
+  FILE_WITHOUT_DEFAULT = "FILE_WITHOUT_DEFAULT",
 }
 
 /**
@@ -20,6 +22,8 @@ export interface ArgumentValueTypes {
   [ArgumentType.BIGINT]: bigint;
   [ArgumentType.FLOAT]: number;
   [ArgumentType.FILE]: string;
+  [ArgumentType.STRING_WITHOUT_DEFAULT]: string | undefined;
+  [ArgumentType.FILE_WITHOUT_DEFAULT]: string | undefined;
 }
 
 /**

diff --git a/v-next/hardhat/test/internal/builtin-plugins/node/json-rpc/handler.ts b/v-next/hardhat/test/internal/builtin-plugins/node/json-rpc/handler.ts
@@ -19,7 +19,7 @@ describe("JSON-RPC handler", function () {
 
   it("should respond to a request with undefined params", async function () {
     const hostname = (await exists("/.dockerenv")) ? "0.0.0.0" : "127.0.0.1";
-    const port = 8545;
+    const port = 8546;
 
     const connection = await hre.network.connect();
     const server = new JsonRpcServerImplementation({

diff --git a/v-next/hardhat/test/internal/core/tasks/task-manager.ts b/v-next/hardhat/test/internal/core/tasks/task-manager.ts
@@ -55,8 +55,8 @@ describe("TaskManagerImplementation", () => {
               globalOption({
                 name: "globalOption1",
                 description: "",
-                type: ArgumentType.STRING,
-                defaultValue: "",
+                type: ArgumentType.STRING_WITHOUT_DEFAULT,
+                defaultValue: undefined,
               }),
             ],
           },
@@ -422,8 +422,8 @@ describe("TaskManagerImplementation", () => {
                   globalOption({
                     name: "arg1",
                     description: "",
-                    type: ArgumentType.STRING,
-                    defaultValue: "",
+                    type: ArgumentType.STRING_WITHOUT_DEFAULT,
+                    defaultValue: undefined,
                   }),
                 ],
               },
@@ -462,8 +462,8 @@ describe("TaskManagerImplementation", () => {
                   globalOption({
                     name: "arg1",
                     description: "",
-                    type: ArgumentType.STRING,
-                    defaultValue: "",
+                    type: ArgumentType.STRING_WITHOUT_DEFAULT,
+                    defaultValue: undefined,
                   }),
                 ],
               },

diff --git a/v-next/hardhat/test/internal/hre-initialization.ts b/v-next/hardhat/test/internal/hre-initialization.ts
@@ -253,7 +253,7 @@ describe("HRE initialization", () => {
           verbose: false,
           version: false,
           myGlobalOption: "default",
-          network: "",
+          network: undefined,
         });
       });
     });