Add rootSchema and ajvOptions options (#196)

Co-authored-by: Sindre Sorhus <sindresorhus@gmail.com>

readme.md

@@ -64,9 +64,7 @@ Type: `object`
 
 [JSON Schema](https://json-schema.org) to validate your config data.
 
-Under the hood, the JSON Schema validator [ajv](https://ajv.js.org/json-schema.html) is used to validate your config. We use [JSON Schema draft-2020-12](https://json-schema.org/draft/2020-12/release-notes) and support all validation keywords and formats.
-
-You should define your schema as an object where each key is the name of your data's property and each value is a JSON schema used to validate that property. See more [here](https://json-schema.org/understanding-json-schema/reference/object.html#properties).
+This will be the [`properties`](https://json-schema.org/understanding-json-schema/reference/object.html#properties) object of the JSON schema. That is, define `schema` as an object where each key is the name of your data's property and each value is a JSON schema used to validate that property. 
 
 Example:
 
@@ -100,6 +98,53 @@ config.set('foo', '1');
 
 **Note:** The `default` value will be overwritten by the `defaults` option if set.
 
+#### rootSchema
+
+Type: `object`
+
+Top-level properties for the schema, excluding `properties` field.
+
+Example:
+
+```js
+import Conf from 'conf';
+
+const store = new Conf({
+	projectName: 'foo',
+	schema: { /* … */ },
+	rootSchema: {
+		additionalProperties: false
+	}
+});
+```
+
+#### ajvOptions
+
+Type: `object`
+
+[Options passed to AJV](https://ajv.js.org/options.html).
+
+Under the hood, the JSON Schema validator [ajv](https://ajv.js.org/json-schema.html) is used to validate your config. We use [JSON Schema draft-2020-12](https://json-schema.org/draft/2020-12/release-notes) and support all validation keywords and formats.
+
+**Note:** By default, `allErrors` and `useDefaults` are both set to `true`, but can be overridden.
+
+Example:
+
+```js
+import Conf from 'conf';
+
+const store = new Conf({
+	projectName: 'foo',
+	schema: { /* … */ },
+	rootSchema: {
+		additionalProperties: false
+	},
+	ajvOptions: {
+		removeAdditional: true
+	}
+});
+```
+
 #### migrations
 
 Type: `object`

source/index.ts

@@ -89,25 +89,27 @@ export default class Conf<T extends Record<string, any> = Record<string, unknown
 
 		this.#options = options;
 
-		if (options.schema) {
-			if (typeof options.schema !== 'object') {
+		if (options.schema ?? options.ajvOptions ?? options.rootSchema) {
+			if (options.schema && typeof options.schema !== 'object') {
 				throw new TypeError('The `schema` option must be an object.');
 			}
 
 			const ajv = new Ajv({
 				allErrors: true,
 				useDefaults: true,
+				...options.ajvOptions,
 			});
 			ajvFormats(ajv);
 
 			const schema: JSONSchema = {
+				...options.rootSchema,
 				type: 'object',
 				properties: options.schema,
 			};
 
 			this.#validator = ajv.compile(schema);
 
-			for (const [key, value] of Object.entries(options.schema) as any) { // TODO: Remove the `as any`.
+			for (const [key, value] of Object.entries(options.schema ?? {}) as any) { // TODO: Remove the `as any`.
 				if (value?.default) {
 					this.#defaultValues[key as keyof T] = value.default; // eslint-disable-line @typescript-eslint/no-unsafe-assignment
 				}

source/types.ts

@@ -1,5 +1,6 @@
 import {type JSONSchema as TypedJSONSchema} from 'json-schema-typed';
 // eslint-disable unicorn/import-index
+import type {CurrentOptions as AjvOptions} from 'ajv/dist/core.js';
 import type Conf from './index.js';
 
 export type Options<T extends Record<string, any>> = {
@@ -13,9 +14,7 @@ export type Options<T extends Record<string, any>> = {
 	/**
 	[JSON Schema](https://json-schema.org) to validate your config data.
 
-	Under the hood, the JSON Schema validator [ajv](https://github.com/epoberezkin/ajv) is used to validate your config. We use [JSON Schema draft-07](https://json-schema.org/latest/json-schema-validation.html) and support all [validation keywords](https://github.com/epoberezkin/ajv/blob/master/KEYWORDS.md) and [formats](https://github.com/epoberezkin/ajv#formats).
-
-	You should define your schema as an object where each key is the name of your data's property and each value is a JSON schema used to validate that property. See more [here](https://json-schema.org/understanding-json-schema/reference/object.html#properties).
+	This will be the [`properties`](https://json-schema.org/understanding-json-schema/reference/object.html#properties) object of the JSON schema. That is, define `schema` as an object where each key is the name of your data's property and each value is a JSON schema used to validate that property.
 
 	@example
 	```
@@ -50,6 +49,49 @@ export type Options<T extends Record<string, any>> = {
 	*/
 	schema?: Schema<T>;
 
+	/**
+	Top-level properties for the schema, excluding `properties` field.
+
+	@example
+	```
+	import Conf from 'conf';
+
+	const store = new Conf({
+		projectName: 'foo',
+		schema: {},
+		rootSchema: {
+			additionalProperties: false
+		}
+	});
+	```
+	*/
+	rootSchema?: Omit<TypedJSONSchema, 'properties'>;
+
+	/**
+	[Options passed to AJV](https://ajv.js.org/options.html).
+
+	Under the hood, the JSON Schema validator [ajv](https://ajv.js.org/json-schema.html) is used to validate your config. We use [JSON Schema draft-2020-12](https://json-schema.org/draft/2020-12/release-notes) and support all validation keywords and formats.
+
+	**Note:** By default, `allErrors` and `useDefaults` are both set to `true`, but can be overridden.
+
+	@example
+	```
+	import Conf from 'conf';
+
+	const store = new Conf({
+		projectName: 'foo',
+		schema: {},
+		rootSchema: {
+			additionalProperties: false
+		},
+		ajvOptions: {
+			removeAdditional: true
+		}
+	});
+	```
+	*/
+	ajvOptions?: AjvOptions;
+
 	/**
 	Name of the config file (without extension).
 
@@ -259,3 +301,5 @@ export type OnDidChangeCallback<T> = (newValue?: T, oldValue?: T) => void;
 export type OnDidAnyChangeCallback<T> = (newValue?: Readonly<T>, oldValue?: Readonly<T>) => void;
 
 export type Unsubscribe = () => void;
+
+export type {CurrentOptions as AjvOptions} from 'ajv/dist/core.js';

test/index.ts

@@ -787,6 +787,32 @@ test('schema - validate Conf default', t => {
 	}, {message: 'Config schema violation: `foo` must be string'});
 });
 
+test('schema - validate rootSchema', t => {
+	t.throws(() => {
+		const config = new Conf({
+			cwd: temporaryDirectory(),
+			rootSchema: {
+				additionalProperties: false,
+			},
+		});
+		config.set('foo', 'bar');
+	}, {message: 'Config schema violation: `` must NOT have additional properties'});
+});
+
+test('AJV - validate AJV options', t => {
+	const config = new Conf({
+		cwd: temporaryDirectory(),
+		ajvOptions: {
+			removeAdditional: true,
+		},
+		rootSchema: {
+			additionalProperties: false,
+		},
+	});
+	config.set('foo', 'bar');
+	t.is(config.get('foo'), undefined);
+});
+
 test('.get() - without dot notation', t => {
 	t.is(t.context.configWithoutDotNotation.get('foo'), undefined);
 	t.is(t.context.configWithoutDotNotation.get('foo', '🐴'), '🐴');