build: add the workaround to ignore Foundry tests when compiling with Hardhat

Author: Yurii721

hardhat.config.ts

@@ -1,7 +1,8 @@
 /* eslint @typescript-eslint/no-non-null-assertion: ["off"] */
 
-import { HardhatUserConfig } from "hardhat/config";
+import { HardhatUserConfig, subtask } from "hardhat/config";
 import type { MultiSolcUserConfig } from "hardhat/src/types/config";
+import { TASK_COMPILE_SOLIDITY_GET_SOURCE_PATHS } from "hardhat/builtin-tasks/task-names";
 /* Uncomment if support of TypeScript `paths` mappings is needed.
  * Make sure to run `pnpm add -D "tsconfig-paths@4.2.0"` in this case.
  */
@@ -22,6 +23,22 @@ dotenv.config();
 
 import "./scripts/tasks/generate-account";
 
+/* Sets the action for the `TASK_COMPILE_SOLIDITY_GET_SOURCE_PATHS` task.
+ *
+ * The approach to ignore Solidity files in `test` directories for Hardhat speeds up its compilation process
+ * significantly. This is especially true in large projects with a lot of Foundry tests.
+ * It can be also extended for deployment scripts as well.
+ * See for more details:
+ * `https://kennysliding.medium.com/how-to-ignore-solidity-files-in-hardhat-compilation-6162963f8c84`
+ */
+subtask(TASK_COMPILE_SOLIDITY_GET_SOURCE_PATHS).setAction(async (_, __, runSuper) => {
+    /* Get the list of source paths that would normally be passed to the Solidity compiler, then
+     * apply a filter function to exclude paths that contain the string "test".
+     */
+    // eslint-disable-next-line @typescript-eslint/no-unsafe-return, @typescript-eslint/no-unsafe-call, @typescript-eslint/no-unsafe-member-access, @typescript-eslint/no-explicit-any
+    return (await runSuper()).filter((p: any) => !p.includes("test"));
+});
+
 const envs = process.env;
 
 // Private keys can be set in `.env` file.