Merge pull request #5264 from NomicFoundation/hre-singleton

Add and test a singleton hre instance

Author: zoeyTM

v-next/hardhat/src/index.ts

@@ -1,9 +1,8 @@
-import { createHardhatRuntimeEnvironment } from "./hre.js";
+import { getHardhatRuntimeEnvironmentSingleton } from "./internal/hre-singleton.js";
 
 // TODO:
-//  - If the HRE was already initialized in the CLI, we should use that one.
 //  - Load the config from the file system.
-const hre = await createHardhatRuntimeEnvironment({});
+const hre = await getHardhatRuntimeEnvironmentSingleton({});
 
 export const { config, tasks, globalArguments, hooks, interruptions } = hre;
 

v-next/hardhat/src/internal/cli/main.ts

@@ -2,7 +2,6 @@ import { isAbsolute, resolve } from "node:path";
 
 import {
   buildGlobalParameterMap,
-  createHardhatRuntimeEnvironment,
   resolvePluginList,
 } from "@nomicfoundation/hardhat-core";
 import {
@@ -14,6 +13,7 @@ import { Task } from "@nomicfoundation/hardhat-core/types/tasks";
 
 import "tsx"; // NOTE: This is important, it allows us to load .ts files form the CLI
 import { builtinPlugins } from "../builtin-plugins/index.js";
+import { getHardhatRuntimeEnvironmentSingleton } from "../hre-singleton.js";
 
 export async function main(cliArguments: string[]) {
   const hreInitStart = performance.now();
@@ -67,6 +67,7 @@ export async function main(cliArguments: string[]) {
 
   if (configPath === undefined) {
     // TODO: Find the closest config file
+    // if HARDHAT_CONFIG exists, use it
     throw new Error("Missing --config");
   }
 
@@ -83,10 +84,13 @@ export async function main(cliArguments: string[]) {
       usedCliArguments,
     );
 
-    const hre = await createHardhatRuntimeEnvironment(
+    const hre = await getHardhatRuntimeEnvironmentSingleton(
       userConfig,
       userProvidedGlobalArguments,
-      { resolvedPlugins, globalParameterMap },
+      {
+        resolvedPlugins,
+        globalParameterMap,
+      },
     );
 
     const hreInitEnd = performance.now();

v-next/hardhat/src/internal/hre-singleton.ts

@@ -0,0 +1,22 @@
+import type { HardhatRuntimeEnvironment } from "../types/hre.js";
+
+import { createHardhatRuntimeEnvironment } from "@nomicfoundation/hardhat-core";
+
+let hre: HardhatRuntimeEnvironment;
+
+/**
+ * This function returns a singleton instance of the Hardhat Runtime Environment.
+ *
+ * It exists so that the CLI and the programmatic API are always using the same HRE instance.
+ *
+ * Note: Only the params of the first call are used.
+ */
+export async function getHardhatRuntimeEnvironmentSingleton(
+  ...params: Parameters<typeof createHardhatRuntimeEnvironment>
+): Promise<HardhatRuntimeEnvironment> {
+  if (hre === undefined) {
+    hre = await createHardhatRuntimeEnvironment(...params);
+  }
+
+  return hre;
+}

v-next/hardhat/test/hre/index.ts

@@ -0,0 +1,35 @@
+import assert from "node:assert/strict";
+import { describe, it } from "node:test";
+
+import { createHardhatRuntimeEnvironment } from "../../src/hre.js";
+import { builtinPlugins } from "../../src/internal/builtin-plugins/index.js";
+import { getHardhatRuntimeEnvironmentSingleton } from "../../src/internal/hre-singleton.js";
+
+describe("HRE", () => {
+  describe("createHardhatRuntimeEnvironment", () => {
+    it("should include the built-in plugins", async () => {
+      const hre = await createHardhatRuntimeEnvironment({});
+
+      assert.deepEqual(hre.config.plugins, builtinPlugins);
+    });
+  });
+
+  describe("getHardhatRuntimeEnvironmentSingleton", () => {
+    it("should return the same instance", async () => {
+      const hre1 = await getHardhatRuntimeEnvironmentSingleton({
+        plugins: [{ id: "custom task" }],
+      });
+      const hre2 = await getHardhatRuntimeEnvironmentSingleton({});
+
+      assert.deepEqual(
+        hre1.config.plugins.find((p) => p.id === "custom task"),
+        { id: "custom task" },
+      );
+      assert.deepEqual(
+        hre2.config.plugins.find((p) => p.id === "custom task"),
+        { id: "custom task" },
+      );
+      assert.deepEqual(hre1, hre2);
+    });
+  });
+});