Add the "require-licence" rule

WIP

WIP

docs/rules/require-license.md

@@ -0,0 +1,76 @@
+# require-license
+
+💼 This rule is enabled in the ✅ `recommended` config.
+
+<!-- end auto-generated rule header -->
+
+This rule applies two validations to the `"licence"` property:
+
+- It must be a string rather than any other data type
+- It's value should match one of the values provided in the options
+
+Example of **incorrect** code for this rule:
+
+When the rule is configured with
+
+```ts
+{
+    "require-license": ["error", "GPL"]
+}
+```
+
+```json
+{
+	"license": "MIT"
+}
+```
+
+When the rule is configured with
+
+```ts
+{
+    "require-license": ["error", ["MIT", "GPL"]]
+}
+```
+
+```json
+{
+	"license": "Apache"
+}
+```
+
+Example of **correct** code for this rule:
+
+When the rule is configured with
+
+```ts
+{
+    "require-license": ["error", "GPL"]
+}
+```
+
+```json
+{
+	"license": "GPL"
+}
+```
+
+When the rule is configured with
+
+```ts
+{
+    "require-license": ["error", ["Apache", "MIT"]]
+}
+```
+
+```json
+{
+	"license": "Apache"
+}
+```
+
+```json
+{
+	"license": "MIT"
+}
+```

src/plugin.ts

@@ -6,6 +6,7 @@ import { rule as noEmptyFields } from "./rules/no-empty-fields.js";
 import { rule as noRedundantFiles } from "./rules/no-redundant-files.js";
 import { rule as orderProperties } from "./rules/order-properties.js";
 import { rule as preferRepositoryShorthand } from "./rules/repository-shorthand.js";
+import { rule as requireLicense } from "./rules/require-license.js";
 import { rule as sortCollections } from "./rules/sort-collections.js";
 import { rule as uniqueDependencies } from "./rules/unique-dependencies.js";
 import { rule as validLocalDependency } from "./rules/valid-local-dependency.js";
@@ -26,6 +27,7 @@ const rules: Record<string, PackageJsonRuleModule> = {
 	"no-redundant-files": noRedundantFiles,
 	"order-properties": orderProperties,
 	"repository-shorthand": preferRepositoryShorthand,
+	"require-license": requireLicense,
 	"sort-collections": sortCollections,
 	"unique-dependencies": uniqueDependencies,
 	"valid-local-dependency": validLocalDependency,

src/rules/require-license.ts

@@ -0,0 +1,80 @@
+import type { AST as JsonAST } from "jsonc-eslint-parser";
+
+import * as ESTree from "estree";
+
+import { createRule } from "../createRule.js";
+
+export type AllowedValues = string | string[];
+export type Options = [AllowedValues];
+
+export function generateReportData(allowed: string[]) {
+	return {
+		allowed: allowed.map((v) => `'${v}'`).join(","),
+		multiple: allowed.length > 1 ? "one of" : "",
+	};
+}
+
+export const rule = createRule<Options>({
+	create(context) {
+		const ruleOptions = context.options[0];
+		const allowedValues = Array.isArray(ruleOptions)
+			? ruleOptions
+			: [ruleOptions];
+		return {
+			"Program > JSONExpressionStatement > JSONObjectExpression > JSONProperty[key.value=license]"(
+				node: JsonAST.JSONProperty,
+			) {
+				if (
+					node.value.type !== "JSONLiteral" ||
+					typeof node.value.value !== "string"
+				) {
+					context.report({
+						messageId: "nonString",
+						node: node.value as unknown as ESTree.Node,
+					});
+					return;
+				}
+
+				if (!allowedValues.includes(node.value.value)) {
+					context.report({
+						data: generateReportData(allowedValues),
+						loc: node.loc,
+						messageId: "invalidValue",
+					});
+				}
+			},
+		};
+	},
+
+	meta: {
+		docs: {
+			category: "Best Practices",
+			description:
+				"Enforce the 'license' field to be a specific value/values",
+			recommended: false,
+		},
+		messages: {
+			invalidValue: '"license" must be{{multiple}} {{allowed}}"',
+			nonString: '"license" must be a string"',
+		},
+		schema: {
+			items: [
+				{
+					oneOf: [
+						{
+							items: {
+								type: "string",
+							},
+							type: "array",
+						},
+						{
+							type: "string",
+						},
+					],
+				},
+			],
+			type: "array",
+		},
+		type: "problem",
+	},
+});

src/tests/rules/require-license.test.ts

@@ -0,0 +1,62 @@
+import { generateReportData, rule } from "../../rules/require-license.js";
+import { ruleTester } from "./ruleTester.js";
+
+ruleTester.run("requires-license", rule, {
+	invalid: [
+		{
+			code: JSON.stringify({
+				license: "CC BY-SA",
+				name: "some-test-package",
+			}),
+			errors: [
+				{
+					data: generateReportData(["GPL"]),
+					messageId: "invalidValue",
+				},
+			],
+			options: ["GPL"],
+		},
+		{
+			code: JSON.stringify({
+				license: "Apache",
+				name: "some-test-package",
+			}),
+			errors: [
+				{
+					data: generateReportData(["MIT", "GPL"]),
+					messageId: "invalidValue",
+				},
+			],
+			options: [["MIT", "GPL"]],
+		},
+		{
+			code: JSON.stringify({
+				license: 1234,
+				name: "some-test-package",
+			}),
+			errors: [
+				{
+					data: generateReportData(["GPL"]),
+					messageId: "nonString",
+				},
+			],
+			options: ["GPL"],
+		},
+	],
+	valid: [
+		{
+			code: JSON.stringify({
+				license: "Apache",
+				name: "some-test-package",
+			}),
+			options: ["Apache"],
+		},
+		{
+			code: JSON.stringify({
+				license: "GPL",
+				name: "some-test-package",
+			}),
+			options: [["MIT", "GPL"]],
+		},
+	],
+});