Add support for less module

.prettierrc

@@ -1,2 +1,3 @@
 {
+  "endOfLine": "auto"
 }

README.md

@@ -89,7 +89,7 @@ module.exports = {
 
 ## Configuration
 
-You can pass an `options` object to configure the loaders and plugins. You can also pass a `modifyLessRule` callback to have full control over the Less webpack rule.
+You can pass an `options` object to configure the loaders and plugins(configure _less_ and _less modules_ at the same time). You can also pass a `modifyLessRule`(or `modifyLessModuleRule`) callback to have full control over the Less webpack rule.
 
 - `options.styleLoaderOptions`
   - _Default:_ `{}`
@@ -112,7 +112,16 @@ You can pass an `options` object to configure the loaders and plugins. You can a
   - A callback function that receives two arguments: the webpack rule, and the context. You must return an updated rule object.
     - `lessRule`:
       - `test`: Regex (default: `/\.less$/`)
-      - `exclude`: Regex (default: `/\.module\.(less)$/`)
+      - `exclude`: Regex (default: `/\.module\.less$/`)
+      - `use`: Array of loaders and options.
+      - `sideEffects`: Boolean (default: same as sass's rule)
+    - `context`:
+      - `env`: "development" or "production"
+      - `paths`: An object with paths, e.g. `appBuild`, `appPath`, `ownNodeModules`
+- `options.modifyLessModuleRule(lessRule, context)`
+  - A callback function that receives two arguments: the webpack rule, and the context. You must return an updated rule object.
+    - `lessModuleRule`:
+      - `test`: Regex (default: `/\.module\.less$/`)
       - `use`: Array of loaders and options.
     - `context`:
       - `env`: "development" or "production"

lib/craco-less.dev.test.js

@@ -4,6 +4,7 @@ const {
   applyCracoConfigPlugins,
   applyWebpackConfigPlugins,
 } = require("@craco/craco/lib/features/plugins");
+const getCSSModuleLocalIdent = require("react-dev-utils/getCSSModuleLocalIdent");
 
 const clone = require("clone");
 
@@ -68,6 +69,37 @@ test("the webpack config is modified correctly without any options", () => {
 
   expect(lessRule.use[4].loader).toContain(`${path.sep}less-loader`);
   expect(lessRule.use[4].options).toEqual({});
+
+  const lessModuleRule = oneOfRule.oneOf.find(
+    (r) => r.test && r.test.toString() === "/\\.module\\.less$/"
+  );
+  expect(lessModuleRule).not.toBeUndefined();
+  expect(lessModuleRule.use[0].loader).toContain(`${path.sep}style-loader`);
+  expect(lessModuleRule.use[0].options).toEqual({});
+
+  expect(lessModuleRule.use[1].loader).toContain(`${path.sep}css-loader`);
+  expect(lessModuleRule.use[1].options).toEqual({
+    importLoaders: 3,
+    sourceMap: webpackConfig.devtool !== false,
+    modules: {
+      getLocalIdent: getCSSModuleLocalIdent,
+    },
+  });
+
+  expect(lessModuleRule.use[2].loader).toContain(`${path.sep}postcss-loader`);
+  expect(lessModuleRule.use[2].options.ident).toEqual("postcss");
+  expect(lessModuleRule.use[2].options.plugins).not.toBeUndefined();
+
+  expect(lessModuleRule.use[3].loader).toContain(
+    `${path.sep}resolve-url-loader`
+  );
+  expect(lessModuleRule.use[3].options).toEqual({
+    root: lessModuleRule.use[3].options.root,
+    sourceMap: webpackConfig.devtool !== false,
+  });
+
+  expect(lessModuleRule.use[4].loader).toContain(`${path.sep}less-loader`);
+  expect(lessModuleRule.use[4].options).toEqual({});
 });
 
 test("the webpack config is modified correctly without any options on Windows", () => {
@@ -127,6 +159,36 @@ test("the webpack config is modified correctly without any options on Windows",
   // We use `require.resolve("less-loader")`, so it's the OS separator here
   expect(lessRule.use[4].loader).toContain(`${path.sep}less-loader`);
   expect(lessRule.use[4].options).toEqual({});
+
+  const lessModuleRule = oneOfRule.oneOf.find(
+    (r) => r.test && r.test.toString() === "/\\.module\\.less$/"
+  );
+  expect(lessModuleRule).not.toBeUndefined();
+  expect(lessModuleRule.use[0].loader).toContain("\\style-loader");
+  expect(lessModuleRule.use[0].options).toEqual({});
+
+  expect(lessModuleRule.use[1].loader).toContain("\\css-loader");
+  expect(lessModuleRule.use[1].options).toEqual({
+    importLoaders: 3,
+    sourceMap: webpackConfig.devtool !== false,
+    modules: {
+      getLocalIdent: getCSSModuleLocalIdent,
+    },
+  });
+
+  expect(lessModuleRule.use[2].loader).toContain("\\postcss-loader");
+  expect(lessModuleRule.use[2].options.ident).toEqual("postcss");
+  expect(lessModuleRule.use[2].options.plugins).not.toBeUndefined();
+
+  expect(lessModuleRule.use[3].loader).toContain(`\\resolve-url-loader`);
+  expect(lessModuleRule.use[3].options).toEqual({
+    root: lessModuleRule.use[3].options.root,
+    sourceMap: webpackConfig.devtool !== false,
+  });
+
+  // We use `require.resolve("less-loader")`, so it's the OS separator here
+  expect(lessModuleRule.use[4].loader).toContain(`${path.sep}less-loader`);
+  expect(lessModuleRule.use[4].options).toEqual({});
 });
 
 test("the webpack config is modified correctly with less-loader options", () => {
@@ -170,6 +232,31 @@ test("the webpack config is modified correctly with less-loader options", () =>
       "@less-variable": "#fff",
     },
   });
+
+  const lessModuleRule = oneOfRule.oneOf.find(
+    (r) => r.test && r.test.toString() === "/\\.module\\.less$/"
+  );
+  expect(lessModuleRule).not.toBeUndefined();
+
+  expect(lessModuleRule.use[2].loader).toContain(`${path.sep}postcss-loader`);
+  expect(lessModuleRule.use[2].options.ident).toEqual("postcss");
+  expect(lessModuleRule.use[2].options.plugins).not.toBeUndefined();
+
+  expect(lessModuleRule.use[3].loader).toContain(
+    `${path.sep}resolve-url-loader`
+  );
+  expect(lessModuleRule.use[3].options).toEqual({
+    root: lessModuleRule.use[3].options.root,
+    sourceMap: webpackConfig.devtool !== false,
+  });
+
+  expect(lessModuleRule.use[4].loader).toContain(`${path.sep}less-loader`);
+  expect(lessModuleRule.use[4].options).toEqual({
+    javascriptEnabled: true,
+    modifyVars: {
+      "@less-variable": "#fff",
+    },
+  });
 });
 
 test("the webpack config is modified correctly with all loader options", () => {
@@ -238,6 +325,43 @@ test("the webpack config is modified correctly with all loader options", () => {
       "@less-variable": "#fff",
     },
   });
+
+  const lessModuleRule = oneOfRule.oneOf.find(
+    (r) => r.test && r.test.toString() === "/\\.module\\.less$/"
+  );
+  expect(lessModuleRule).not.toBeUndefined();
+  expect(lessModuleRule.use[0].loader).toContain(`${path.sep}style-loader`);
+  expect(lessModuleRule.use[0].options).toEqual({
+    sourceMaps: true,
+  });
+
+  expect(lessModuleRule.use[1].loader).toContain(`${path.sep}css-loader`);
+  expect(lessModuleRule.use[1].options).toEqual({
+    modules: true,
+    importLoaders: 3,
+    localIdentName: "[local]_[hash:base64:5]",
+    sourceMap: webpackConfig.devtool !== false,
+  });
+
+  expect(lessModuleRule.use[2].loader).toContain(`${path.sep}postcss-loader`);
+  expect(lessModuleRule.use[2].options.ident).toEqual("test-ident");
+  expect(lessModuleRule.use[2].options.plugins).not.toBeUndefined();
+
+  expect(lessModuleRule.use[3].loader).toContain(
+    `${path.sep}resolve-url-loader`
+  );
+  expect(lessModuleRule.use[3].options).toEqual({
+    root: lessModuleRule.use[3].options.root,
+    sourceMap: webpackConfig.devtool !== false,
+  });
+
+  expect(lessModuleRule.use[4].loader).toContain(`${path.sep}less-loader`);
+  expect(lessModuleRule.use[4].options).toEqual({
+    javascriptEnabled: true,
+    modifyVars: {
+      "@less-variable": "#fff",
+    },
+  });
 });
 
 test("the webpack config is modified correctly with the modifyLessRule option", () => {
@@ -283,6 +407,71 @@ test("the webpack config is modified correctly with the modifyLessRule option",
   expect(lessRule.use[4].options).toEqual({});
 });
 
+test("the webpack config is modified correctly with the modifyLessModuleRule option", () => {
+  applyCracoConfigAndOverrideWebpack({
+    plugins: [
+      {
+        plugin: CracoLessPlugin,
+        options: {
+          modifyLessModuleRule: (rule, context) => {
+            if (context.env === "production") {
+              rule.use[0].options.testOption = "test-value-production";
+              rule.use[1].options.modules.getLocalIdent =
+                "test-deep-clone-production";
+            } else {
+              rule.use[0].options.testOption = "test-value-development";
+              rule.use[1].options.modules.getLocalIdent =
+                "test-deep-clone-development";
+            }
+            return rule;
+          },
+        },
+      },
+    ],
+  });
+
+  const oneOfRule = webpackConfig.module.rules.find((r) => r.oneOf);
+  expect(oneOfRule).not.toBeUndefined();
+  const lessModuleRule = oneOfRule.oneOf.find(
+    (r) => r.test && r.test.toString() === "/\\.module\\.less$/"
+  );
+  expect(lessModuleRule).not.toBeUndefined();
+
+  expect(lessModuleRule.use[0].loader).toContain(`${path.sep}style-loader`);
+  expect(lessModuleRule.use[0].options.testOption).toEqual(
+    "test-value-development"
+  );
+
+  expect(lessModuleRule.use[1].options.modules.getLocalIdent).toEqual(
+    "test-deep-clone-development"
+  );
+
+  expect(lessModuleRule.use[2].loader).toContain(`${path.sep}postcss-loader`);
+  expect(lessModuleRule.use[2].options.ident).toEqual("postcss");
+  expect(lessModuleRule.use[2].options.plugins).not.toBeUndefined();
+
+  expect(lessModuleRule.use[3].loader).toContain(
+    `${path.sep}resolve-url-loader`
+  );
+  expect(lessModuleRule.use[3].options).toEqual({
+    root: lessModuleRule.use[3].options.root,
+    sourceMap: webpackConfig.devtool !== false,
+  });
+
+  expect(lessModuleRule.use[4].loader).toContain(`${path.sep}less-loader`);
+  expect(lessModuleRule.use[4].options).toEqual({});
+
+  const sassModuleRule = oneOfRule.oneOf.find((rule) => {
+    if (!rule.test) return false;
+    const test = rule.test.toString();
+    return test.includes("scss|sass") && test.includes("module");
+  });
+
+  expect(sassModuleRule.use[1].options.modules.getLocalIdent).toEqual(
+    getCSSModuleLocalIdent
+  );
+});
+
 test("throws an error when we can't find file-loader in the webpack config", () => {
   let oneOfRule = webpackConfig.module.rules.find((r) => r.oneOf);
   oneOfRule.oneOf = oneOfRule.oneOf.filter(
@@ -343,9 +532,11 @@ test("throws an error when we can't find the oneOf rules in the webpack config",
 
 test("throws an error when react-scripts adds an unknown webpack rule", () => {
   let oneOfRule = webpackConfig.module.rules.find((r) => r.oneOf);
-  const sassRule = oneOfRule.oneOf.find((rule) =>
-    rule.test.toString().includes("scss|sass")
-  );
+  const sassRule = oneOfRule.oneOf.find((rule) => {
+    if (!rule.test) return false;
+    const test = rule.test.toString();
+    return test.includes("scss|sass") && !test.includes("module");
+  });
   sassRule.use.push({
     loader: "/path/to/unknown-loader/index.js",
   });
@@ -364,9 +555,11 @@ test("throws an error when react-scripts adds an unknown webpack rule", () => {
 
 test("throws an error when the sass rule is missing", () => {
   let oneOfRule = webpackConfig.module.rules.find((r) => r.oneOf);
-  oneOfRule.oneOf = oneOfRule.oneOf.filter(
-    (rule) => !(rule.test && rule.test.toString().includes("scss|sass"))
-  );
+  oneOfRule.oneOf = oneOfRule.oneOf.filter((rule) => {
+    if (!rule.test) return true;
+    const test = rule.test.toString();
+    return !(test.includes("scss|sass") && !test.includes("module"));
+  });
   const runTest = () => {
     applyCracoConfigAndOverrideWebpack({
       plugins: [{ plugin: CracoLessPlugin }],
@@ -379,3 +572,23 @@ test("throws an error when the sass rule is missing", () => {
     )
   );
 });
+
+test("throws an error when the sass module rule is missing", () => {
+  let oneOfRule = webpackConfig.module.rules.find((r) => r.oneOf);
+  oneOfRule.oneOf = oneOfRule.oneOf.filter((rule) => {
+    if (!rule.test) return true;
+    const test = rule.test.toString();
+    return !(test.includes("scss|sass") && test.includes("module"));
+  });
+  const runTest = () => {
+    applyCracoConfigAndOverrideWebpack({
+      plugins: [{ plugin: CracoLessPlugin }],
+    });
+  };
+  expect(runTest).toThrowError(
+    new RegExp(
+      "Can't find the webpack rule to match scss/sass module files in the " +
+        "development webpack config!"
+    )
+  );
+});