ESM Support

lib/env/config.js

@@ -1,6 +1,8 @@
 const fs = require("fs-extra");
 const path = require("path");
+const url = require("url");
 const { get } = require("lodash");
+const moduleLoader = require('../utils/module-loader');
 
 const DEFAULT_CONFIG_FILE_NAME = "migrate-mongo-config.js";
 
@@ -60,6 +62,14 @@ module.exports = {
       return customConfigContent;
     }
     const configPath = getConfigPath();
-    return Promise.resolve(require(configPath)); // eslint-disable-line
+    try {
+      return Promise.resolve(moduleLoader.require(configPath));
+    } catch (e) {
+      if (e.code === 'ERR_REQUIRE_ESM') {
+        const loadedImport = await moduleLoader.import(url.pathToFileURL(configPath));
+        return loadedImport.default
+      }
+      throw e;
+    }
   }
 };

lib/env/migrationsDir.js

@@ -1,7 +1,9 @@
 const fs = require("fs-extra");
 const path = require("path");
+const url = require("url");
 const crypto = require("crypto");
 const config = require("./config");
+const moduleLoader = require('../utils/module-loader');
 
 const DEFAULT_MIGRATIONS_DIR_NAME = "migrations";
 const DEFAULT_MIGRATION_EXT = ".js";
@@ -94,11 +96,19 @@ module.exports = {
 
   async loadMigration(fileName) {
     const migrationsDir = await resolveMigrationsDirPath();
-    return require(path.join(migrationsDir, fileName)); // eslint-disable-line
+    const migrationPath = path.join(migrationsDir, fileName);
+    try {
+      return moduleLoader.require(migrationPath);
+    } catch (e) {
+      if (e.code === 'ERR_REQUIRE_ESM') {
+        return moduleLoader.import(url.pathToFileURL(migrationPath));
+      }
+      throw e;
+    }
   },
 
   async loadFileHash(fileName) {
-    const migrationsDir = await resolveMigrationsDirPath(); 
+    const migrationsDir = await resolveMigrationsDirPath();
     const filePath = path.join(migrationsDir, fileName)
     const hash = crypto.createHash('sha256');
     const input = await fs.readFile(filePath);

lib/utils/module-loader.js

@@ -0,0 +1,10 @@
+module.exports = {
+  require(requirePath) {
+    return require(requirePath); // eslint-disable-line
+  },
+
+  /* istanbul ignore next */
+  import(importPath) {
+    return import(importPath); // eslint-disable-line
+  },
+};

test/env/config.test.js

@@ -7,16 +7,27 @@ const path = require("path");
 describe("config", () => {
   let config; // module under test
   let fs; // mocked dependencies
+  let moduleLoader;
 
   function mockFs() {
     return {
       stat: sinon.stub()
     };
   }
 
+  function mockModuleLoader() {
+    return {
+      import: sinon.stub(),
+    };
+  }
+
   beforeEach(() => {
     fs = mockFs();
-    config = proxyquire("../../lib/env/config", { "fs-extra": fs });
+    moduleLoader = mockModuleLoader();
+    config = proxyquire("../../lib/env/config", {
+      "fs-extra": fs,
+      "../utils/module-loader": moduleLoader
+    });
   });
 
   describe("shouldExist()", () => {
@@ -98,19 +109,17 @@ describe("config", () => {
         await config.read();
         expect.fail("Error was not thrown");
       } catch (err) {
-        expect(err.message).to.match(new RegExp(`Cannot find module '${configPath}'`));
+        expect(err.message).to.have.string(`Cannot find module '${configPath}'`);
       }
     });
 
     it("should be possible to read a custom, absolute config file path", async () => {
-      global.options = { file: "/some/absoluete/path/to/a-config-file.js" };
+      global.options = { file: "/some/absolute/path/to/a-config-file.js" };
       try {
         await config.read();
         expect.fail("Error was not thrown");
       } catch (err) {
-        expect(err.message).to.match(
-          new RegExp(`Cannot find module '${global.options.file}'`)
-        );
+        expect(err.message).to.have.string(`Cannot find module '${global.options.file}'`);
       }
     });
 
@@ -121,8 +130,17 @@ describe("config", () => {
         await config.read();
         expect.fail("Error was not thrown");
       } catch (err) {
-        expect(err.message).to.match(new RegExp(`Cannot find module '${configPath}'`));
+        expect(err.message).to.have.string(`Cannot find module '${configPath}'`);
       }
     });
+
+    it("should fall back to using 'import' if Node requires the use of ESM", async () => {
+      const error = new Error('ESM required');
+      error.code = 'ERR_REQUIRE_ESM';
+      moduleLoader.require = sinon.stub().throws(error);
+      moduleLoader.import.returns({});
+      await config.read();
+      expect(moduleLoader.import.called).to.equal(true);
+    });
   });
 });

test/env/migrationsDir.test.js

@@ -8,6 +8,7 @@ describe("migrationsDir", () => {
   let migrationsDir;
   let fs;
   let config;
+  let moduleLoader;
 
   function mockFs() {
     return {
@@ -26,12 +27,20 @@ describe("migrationsDir", () => {
     };
   }
 
+  function mockModuleLoader() {
+    return {
+      import: sinon.stub(),
+    };
+  }
+
   beforeEach(() => {
     fs = mockFs();
     config = mockConfig();
+    moduleLoader = mockModuleLoader();
     migrationsDir = proxyquire("../../lib/env/migrationsDir", {
       "fs-extra": fs,
-      "./config": config
+      "./config": config,
+      "../utils/module-loader": moduleLoader
     });
   });
 
@@ -165,9 +174,17 @@ describe("migrationsDir", () => {
         await migrationsDir.loadMigration("someFile.js");
         expect.fail("Error was not thrown");
       } catch (err) {
-        expect(err.message).to.match(new RegExp(`Cannot find module '${pathToMigration}'`));
+        expect(err.message).to.have.string(`Cannot find module '${pathToMigration}'`);
       }
     });
+
+    it("should fall back to using 'import' if Node requires the use of ESM", async () => {
+      const error = new Error('ESM required');
+      error.code = 'ERR_REQUIRE_ESM';
+      moduleLoader.require = sinon.stub().throws(error);
+      await migrationsDir.loadMigration("someFile.js");
+      expect(moduleLoader.import.called).to.equal(true);
+    });
   });
 
   describe("resolveMigrationFileExtension()", () => {