feat(eslint-plugin): add no-missing-exports rule (#2612)

Author: v-oss891

packages/eslint-plugin-pinia/package.json

@@ -0,0 +1,13 @@
+{
+    "name": "@pinia/eslint-plugin",
+    "version": "0.0.1",
+    "main": "src/index.js",
+    "type": "commonjs",
+    "peerDependencies": {
+      "eslint": "^8.0.0"
+    },
+    "scripts": {
+      "test": "eslint --rule 'pinia/no-missing-exports: error' tests/*.js && node tests/no-missing-exports.test.js"
+    }
+  }
+  

packages/eslint-plugin-pinia/src/configs/recommended.js

@@ -0,0 +1,6 @@
+module.exports = {
+    rules: {
+      "pinia/no-missing-exports": "warn"
+    }
+  };
+  

packages/eslint-plugin-pinia/src/index.js

@@ -0,0 +1,10 @@
+module.exports = {
+    rules: {
+      "no-missing-exports": require("./rules/no-missing-exports"),
+    },
+  
+    configs: {
+      recommended: require("./configs/recommended"),
+    }
+  };
+  

packages/eslint-plugin-pinia/src/rules/no-missing-exports.js

@@ -0,0 +1,61 @@
+/**
+ * Rule goal:
+ * Warn when variables declared inside a Pinia setup store
+ * are NOT returned in the final return statement.
+ */
+
+module.exports = {
+    meta: {
+      type: "problem",
+      docs: {
+        description:
+          "Warn when variables declared inside a setup store are not exported via return()",
+      },
+      schema: [],
+    },
+  
+    create(context) {
+      return {
+        ReturnStatement(node) {
+          const returnedNames = new Set();
+  
+          // read return object properties (return { a, b })
+          if (node.argument && node.argument.properties) {
+            for (const prop of node.argument.properties) {
+              if (prop.key && prop.key.name) {
+                returnedNames.add(prop.key.name);
+              }
+            }
+          }
+  
+          // find variable declarations in the same function
+          const fn = context
+            .getAncestors()
+            .reverse()
+            .find(
+              (n) =>
+                n.type === "FunctionDeclaration" ||
+                n.type === "FunctionExpression" ||
+                n.type === "ArrowFunctionExpression"
+            );
+  
+          if (!fn || !fn.body || !fn.body.body) return;
+  
+          for (const stmt of fn.body.body) {
+            if (stmt.type === "VariableDeclaration") {
+              for (const decl of stmt.declarations) {
+                const name = decl.id.name;
+                if (!returnedNames.has(name)) {
+                  context.report({
+                    node: decl,
+                    message: `Variable '${name}' is declared but not exported via return()`,
+                  });
+                }
+              }
+            }
+          }
+        },
+      };
+    },
+  };
+  

packages/eslint-plugin-pinia/tests/no-missing-exports.test.js

@@ -0,0 +1,29 @@
+const rule = require("../src/rules/no-missing-exports");
+const { RuleTester } = require("eslint");
+
+const tester = new RuleTester({
+  parserOptions: { ecmaVersion: 2020, sourceType: "module" }
+});
+
+tester.run("no-missing-exports", rule, {
+  valid: [
+    `
+    export const useX = defineStore('x', () => {
+      const a = 1;
+      return { a };
+    });
+    `
+  ],
+  invalid: [
+    {
+      code: `
+      export const useX = defineStore('x', () => {
+        const a = 1;
+        const b = 2;
+        return { a };
+      });
+      `,
+      errors: [{ message: "Variable 'b' is declared but not exported via return()" }]
+    }
+  ]
+});