feat: add @git-validator/no-untyped-empty-array, close #229

.changeset/wise-moose-allow.md

@@ -0,0 +1,6 @@
+---
+"@git-validator/eslint-config": patch
+"@git-validator/eslint-plugin": patch
+---
+
+feat: add `@git-validator/no-untyped-empty-array`

packages/eslint-config/src/ts-config.ts

@@ -126,6 +126,7 @@ const mainConfig = {
     "@git-validator/no-declares-in-ts-file": "error",
     "@git-validator/no-export-assignment": "error",
     "@git-validator/no-property-decorator": "error",
+    "@git-validator/no-untyped-empty-array": "error",
     // typescript
     "@typescript-eslint/await-thenable": "error",
     "@typescript-eslint/ban-ts-comment": [

packages/eslint-plugin/src/index.ts

@@ -11,6 +11,7 @@ import noInstanceofBuiltin from "./rules/no-instanceof-builtin.js";
 import noLegacyGetterSetter from "./rules/no-legacy-getter-setter.js";
 import noPropertyDecorator from "./rules/no-property-decorator.js";
 import noRelativeParentImports from "./rules/no-relative-parent-imports.js";
+import noUntypedEmptyArray from "./rules/no-untyped-empty-array.js";
 import preferGlobalThis from "./rules/prefer-global-this.js";
 import preferShortestRelativePath from "./rules/prefer-shortest-relative-path.js";
 import requireReduceInitialValue from "./rules/require-reduce-initial-value.js";
@@ -30,6 +31,7 @@ export default {
     [noLegacyGetterSetter.name]: noLegacyGetterSetter.rule,
     [noPropertyDecorator.name]: noPropertyDecorator.rule,
     [noRelativeParentImports.name]: noRelativeParentImports.rule,
+    [noUntypedEmptyArray.name]: noUntypedEmptyArray.rule,
     [preferGlobalThis.name]: preferGlobalThis.rule,
     [preferShortestRelativePath.name]: preferShortestRelativePath.rule,
     [requireReduceInitialValue.name]: requireReduceInitialValue.rule,

packages/eslint-plugin/src/rules/no-untyped-empty-array.spec.ts

@@ -0,0 +1,22 @@
+import rule from "./no-untyped-empty-array.js";
+import { test } from "./utils.spec.js";
+
+const valid = [
+  "const arr: number[] = []",
+  "const arr: any[] = []",
+  "const arr = [] as unknown[]",
+  "const arr = ['foo']",
+  "const arr = [[]]",
+  "const arr = [{}]",
+  "class A {names = []}",
+];
+
+const invalid = [
+  "const arr = []",
+  "let arr = []",
+  "var arr = []",
+  "let arr1=[],arr2",
+  "var arr1,arr2=[]",
+];
+
+test({ valid, invalid, ...rule });

packages/eslint-plugin/src/rules/no-untyped-empty-array.ts

@@ -0,0 +1,24 @@
+import { createSimpleRule, getRuleName } from "../utils.js";
+
+export default createSimpleRule({
+  name: getRuleName(import.meta.url),
+  message:
+    "Defining a variable with an empty array should annotate the array type",
+  create: (context) => ({
+    VariableDeclaration: (node) => {
+      node.declarations.forEach((declaration) => {
+        const { init, id } = declaration;
+        if (init?.type !== "ArrayExpression") {
+          return;
+        }
+        if (init.elements.length > 0) {
+          return;
+        }
+        if (id.typeAnnotation) {
+          return;
+        }
+        context.reportNode(declaration);
+      });
+    },
+  }),
+});