Add and test a singleton hre instance

v-next/hardhat/src/index.ts

@@ -1,9 +1,8 @@
-import { createHardhatRuntimeEnvironment } from "./hre.js";
+import { getHRE } 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 getHRE({});
 
 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 { getHRE } 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");
   }
 
@@ -83,11 +84,10 @@ export async function main(cliArguments: string[]) {
       usedCliArguments,
     );
 
-    const hre = await createHardhatRuntimeEnvironment(
-      userConfig,
-      userProvidedGlobalArguments,
-      { resolvedPlugins, globalParameterMap },
-    );
+    const hre = await getHRE(userConfig, userProvidedGlobalArguments, {
+      resolvedPlugins,
+      globalParameterMap,
+    });
 
     const hreInitEnd = performance.now();
     console.log("Time to initialize the HRE (ms):", hreInitEnd - hreInitStart);

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

@@ -0,0 +1,20 @@
+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.
+ */
+export async function getHRE(
+  ...params: Parameters<typeof createHardhatRuntimeEnvironment>
+): Promise<HardhatRuntimeEnvironment> {
+  if (hre === undefined) {
+    hre = await createHardhatRuntimeEnvironment(...params);
+  }
+
+  return hre;
+}

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

@@ -0,0 +1,33 @@
+import assert from "node:assert";
+import { describe, it } from "node:test";
+
+import { createHardhatRuntimeEnvironment } from "../../src/hre.js";
+import { builtinPlugins } from "../../src/internal/builtin-plugins/index.js";
+import { getHRE } from "../../src/internal/hre-singleton.js";
+
+describe("HRE", () => {
+  describe("createHardhatRuntimeEnvironment", () => {
+    it("should include the built-in plugins", async () => {
+      const hre = await createHardhatRuntimeEnvironment({});
+
+      assert.deepStrictEqual(hre.config.plugins, builtinPlugins);
+    });
+  });
+
+  describe("getHRE", () => {
+    it("should return the same instance", async () => {
+      const hre1 = await getHRE({ plugins: [{ id: "custom task" }] });
+      const hre2 = await getHRE({});
+
+      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.deepStrictEqual(hre1, hre2);
+    });
+  });
+});