feat(require-author): add new require-author rule (#851)

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## PR Checklist

-   [x] Addresses an existing open issue: fixes #795 
- [x] That issue was marked as [`status: accepting
prs`](https://github.com/JoshuaKGoldberg/eslint-plugin-package-json/issues?q=is%3Aopen+is%3Aissue+label%3A%22status%3A+accepting+prs%22)
- [x] Steps in
[CONTRIBUTING.md](https://github.com/JoshuaKGoldberg/eslint-plugin-package-json/blob/main/.github/CONTRIBUTING.md)
were taken

## Overview

This change adds the first or our new `require-` rules, and creates some
foundational plumbing to make it super easy to add new require rules.
I've only done author in this PR. Assuming this all looks good, we can
quickly knock all the rest of the require rules in one shot.

README.md

@@ -126,6 +126,7 @@ The default settings don't conflict, and Prettier plugins can quickly fix up ord
 | [no-redundant-files](docs/rules/no-redundant-files.md)                 | Prevents adding unnecessary / redundant files.                                                    |    |    | 💡 |    |
 | [order-properties](docs/rules/order-properties.md)                     | Package properties must be declared in standard order                                             | ✅  | 🔧 |    |    |
 | [repository-shorthand](docs/rules/repository-shorthand.md)             | Enforce either object or shorthand declaration for repository.                                    | ✅  | 🔧 |    |    |
+| [require-author](docs/rules/require-author.md)                         | Requires the `author` property to be present.                                                     |    |    |    |    |
 | [sort-collections](docs/rules/sort-collections.md)                     | Dependencies, scripts, and configuration values must be declared in alphabetical order.           | ✅  | 🔧 |    |    |
 | [unique-dependencies](docs/rules/unique-dependencies.md)               | Checks a dependency isn't specified more than once (i.e. in `dependencies` and `devDependencies`) | ✅  |    | 💡 |    |
 | [valid-local-dependency](docs/rules/valid-local-dependency.md)         | Checks existence of local dependencies in the package.json                                        | ✅  |    |    |    |

docs/rules/require-author.md

@@ -0,0 +1,25 @@
+# require-author
+
+<!-- end auto-generated rule header -->
+
+This rule checks for the existence of the `"author"` property in a package.json,
+and reports a violation if it doesn't exist.
+
+Example of **incorrect** code for this rule:
+
+```json
+{
+	"name": "thee-silver-mt-zion",
+	"version": "13.0.0"
+}
+```
+
+Example of **correct** code for this rule:
+
+```json
+{
+	"name": "thee-silver-mt-zion",
+	"version": "13.0.0",
+	"author": "Jessica Moss"
+}
+```

package.json

@@ -39,7 +39,7 @@
 		"build": "tsup",
 		"format": "prettier \"**/*\" --ignore-unknown",
 		"lint": "eslint . --max-warnings 0",
-		"lint:eslint-docs": "npm run update:eslint-docs -- --check",
+		"lint:eslint-docs": "pnpm update:eslint-docs --check",
 		"lint:knip": "knip",
 		"lint:md": "markdownlint \"**/*.md\" \".github/**/*.md\"",
 		"lint:packages": "pnpm dedupe --check",

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 { rules as requireRules } from "./rules/require-properties.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";
@@ -25,6 +26,7 @@ const rules: Record<string, PackageJsonRuleModule> = {
 	"no-empty-fields": noEmptyFields,
 	"no-redundant-files": noRedundantFiles,
 	"order-properties": orderProperties,
+	...requireRules,
 	"repository-shorthand": preferRepositoryShorthand,
 	"sort-collections": sortCollections,
 	"unique-dependencies": uniqueDependencies,

src/rules/require-properties.ts

@@ -0,0 +1,22 @@
+import type { PackageJsonRuleModule } from "../createRule.js";
+
+import { createRequirePropertyRule } from "../utils/createRequirePropertyRule.js";
+
+// List of all properties we want to create require- rules for,
+// in the format [propertyName, isRecommended]
+const properties = [
+	["author", false],
+	// TODO: More to come!
+] satisfies [string, boolean][];
+
+/** All require- flavor rules */
+export const rules = properties.reduce<Record<string, PackageJsonRuleModule>>(
+	(acc, [propertyName, isRecommended]) => {
+		acc[`require-${propertyName}`] = createRequirePropertyRule(
+			propertyName,
+			isRecommended,
+		);
+		return acc;
+	},
+	{},
+);

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

@@ -0,0 +1,54 @@
+import { rules } from "../../rules/require-properties.js";
+import { ruleTester } from "./ruleTester.js";
+
+ruleTester.run("require-author", rules["require-author"], {
+	invalid: [
+		{
+			code: "{}",
+			errors: [
+				{
+					data: { property: "author" },
+					line: 1,
+					messageId: "missing",
+				},
+			],
+		},
+		{
+			code: `{
+            "name": "foo",
+            "version": "1.0.0"
+            }
+            `,
+			errors: [
+				{
+					data: { property: "author" },
+					line: 1,
+					messageId: "missing",
+				},
+			],
+		},
+		{
+			code: `{
+            "name": "foo",
+            "version": "1.0.0",
+            "bin": {
+                "author": "./cli.js"
+            }
+            }
+            `,
+			errors: [
+				{
+					data: { property: "author" },
+					line: 1,
+					messageId: "missing",
+				},
+			],
+		},
+	],
+	valid: [
+		`{ "main": "./index.js", "author": "Sophie Trudeau" }`,
+		`{ "author": "Jessica Moss" }`,
+		`{ "author": 123 }`,
+		`{ "author": { "name": "Jessica Moss" } }`,
+	],
+});

src/utils/createRequirePropertyRule.ts

@@ -0,0 +1,48 @@
+import type { AST as JsonAST } from "jsonc-eslint-parser";
+
+import { createRule } from "../createRule.js";
+import { isJSONStringLiteral } from "./predicates.js";
+
+/**
+ * Given a top-level property name, create a rule that requires that property to be present.
+ * Optionally, include it in the recommended config.
+ */
+export const createRequirePropertyRule = (
+	propertyName: string,
+	isRecommended = false,
+) => {
+	return createRule({
+		create(context) {
+			return {
+				"Program > JSONExpressionStatement > JSONObjectExpression"(
+					node: JsonAST.JSONObjectExpression,
+				) {
+					if (
+						!node.properties.some(
+							(property) =>
+								isJSONStringLiteral(property.key) &&
+								property.key.value === propertyName,
+						)
+					) {
+						context.report({
+							data: { property: propertyName },
+							messageId: "missing",
+							node: context.sourceCode.ast,
+						});
+					}
+				},
+			};
+		},
+		meta: {
+			docs: {
+				description: `Requires the \`${propertyName}\` property to be present.`,
+				recommended: isRecommended,
+			},
+			messages: {
+				missing: "Property '{{property}}' is required.",
+			},
+			schema: [],
+			type: "suggestion",
+		},
+	});
+};