feat: simplify base class hierarchy (#1543)

BREAKING CHANGE: `mixed` schema are no longer treated as the base class for other schema types. It hasn't been for a while, but we've done some nasty prototype slinging to make it behave like it was. Now typescript types should be 1 to 1 with the actual classes yup exposes. 

In general this should not affect anything unless you are extending (via `addMethod` or otherwise) `mixed` prototype. 

```diff
import {
-  mixed,
+  Schema,
} from 'yup';

- addMethod(mixed, 'method', impl)
+ addMethod(Schema, 'method', impl)
```

docs/extending.md

@@ -49,7 +49,7 @@ Note that `addMethod` isn't magic, it mutates the prototype of the passed in sch
 
 If you're use case calls for creating an entirely new type. inheriting from
 and existing schema class may be best: Generally you should not inheriting from
-the abstract `BaseSchema` unless you know what you are doing. The other types are fair game though.
+the abstract `Schema` unless you know what you are doing. The other types are fair game though.
 
 You should keep in mind some basic guidelines when extending schemas:
 

src/Lazy.ts

@@ -8,7 +8,7 @@ import type {
   SchemaLazyDescription,
 } from './schema';
 import { Flags, ISchema } from './util/types';
-import { BaseSchema } from '.';
+import { Schema } from '.';
 
 export type LazyBuilder<
   T,
@@ -60,8 +60,8 @@ class Lazy<T, TContext = AnyObject, TDefault = any, TFlags extends Flags = any>
   private _resolve = (
     value: any,
     options: ResolveOptions<TContext> = {},
-  ): BaseSchema<T, TContext, TDefault, TFlags> => {
-    let schema = this.builder(value, options) as BaseSchema<
+  ): Schema<T, TContext, TDefault, TFlags> => {
+    let schema = this.builder(value, options) as Schema<
       T,
       TContext,
       TDefault,

src/array.ts

@@ -22,7 +22,7 @@ import {
   ISchema,
   UnsetFlag,
 } from './util/types';
-import BaseSchema, { SchemaInnerTypeDescription, SchemaSpec } from './schema';
+import Schema, { SchemaInnerTypeDescription, SchemaSpec } from './schema';
 import { ResolveOptions } from './Condition';
 
 export type RejectorFn = (
@@ -43,7 +43,7 @@ export default class ArraySchema<
   TDefault = undefined,
   TFlags extends Flags = '',
   TIn extends any[] | null | undefined = T[] | undefined,
-> extends BaseSchema<TIn, TContext, TDefault, TFlags> {
+> extends Schema<TIn, TContext, TDefault, TFlags> {
   innerType?: ISchema<T, TContext>;
 
   constructor(type?: ISchema<T, TContext>) {
@@ -289,7 +289,7 @@ export default interface ArraySchema<
   TDefault = undefined,
   TFlags extends Flags = '',
   TIn extends any[] | null | undefined = T[] | undefined,
-> extends BaseSchema<TIn, TContext, TDefault, TFlags> {
+> extends Schema<TIn, TContext, TDefault, TFlags> {
   default<D extends Maybe<TIn>>(
     def: Thunk<D>,
   ): ArraySchema<T, TContext, D, ToggleDefault<TFlags, D>, TIn>;

src/boolean.ts

@@ -1,4 +1,4 @@
-import BaseSchema from './schema';
+import Schema from './schema';
 import type { AnyObject, Maybe, Message, Optionals } from './types';
 import type {
   Defined,
@@ -26,7 +26,7 @@ export default class BooleanSchema<
   TContext = AnyObject,
   TDefault = undefined,
   TFlags extends Flags = '',
-> extends BaseSchema<TType, TContext, TDefault, TFlags> {
+> extends Schema<TType, TContext, TDefault, TFlags> {
   constructor() {
     super({
       type: 'boolean',

src/date.ts

@@ -13,7 +13,7 @@ import type {
   ToggleDefault,
   UnsetFlag,
 } from './util/types';
-import BaseSchema from './schema';
+import Schema from './schema';
 
 let invalidDate = new Date('');
 
@@ -34,7 +34,7 @@ export default class DateSchema<
   TContext = AnyObject,
   TDefault = undefined,
   TFlags extends Flags = '',
-> extends BaseSchema<TType, TContext, TDefault, TFlags> {
+> extends Schema<TType, TContext, TDefault, TFlags> {
   static INVALID_DATE = invalidDate;
 
   constructor() {
@@ -113,7 +113,7 @@ export default interface DateSchema<
   TContext = AnyObject,
   TDefault = undefined,
   TFlags extends Flags = '',
-> extends BaseSchema<TType, TContext, TDefault, TFlags> {
+> extends Schema<TType, TContext, TDefault, TFlags> {
   default<D extends Maybe<TType>>(
     def: Thunk<D>,
   ): DateSchema<TType, TContext, D, ToggleDefault<TFlags, D>>;

src/index.ts

@@ -1,7 +1,7 @@
-import Mixed, {
+import MixedSchema, {
   create as mixedCreate,
-  MixedSchema,
   MixedOptions,
+  TypeGuard,
 } from './mixed';
 import BooleanSchema, { create as boolCreate } from './boolean';
 import StringSchema, { create as stringCreate } from './string';
@@ -15,7 +15,7 @@ import ValidationError from './ValidationError';
 import reach from './util/reach';
 import isSchema from './util/isSchema';
 import setLocale from './setLocale';
-import BaseSchema, { AnySchema } from './schema';
+import Schema, { AnySchema } from './schema';
 import type { InferType } from './util/types';
 
 function addMethod<T extends AnySchema>(
@@ -48,6 +48,7 @@ export type {
   InferType as Asserts,
   AnySchema,
   MixedOptions,
+  TypeGuard,
 };
 
 export {
@@ -69,9 +70,8 @@ export {
 };
 
 export {
-  BaseSchema,
-  Mixed as MixedSchema,
-  MixedSchema as MixedSchemaClass,
+  Schema,
+  MixedSchema,
   BooleanSchema,
   StringSchema,
   NumberSchema,

src/mixed.ts

@@ -8,14 +8,42 @@ import type {
   ToggleDefault,
   UnsetFlag,
 } from './util/types';
-import BaseSchema from './schema';
+import Schema from './schema';
 
-export declare class MixedSchema<
+const returnsTrue: any = () => true;
+
+export type TypeGuard<TType> = (value: any) => value is NonNullable<TType>;
+export interface MixedOptions<TType> {
+  type?: string;
+  check?: TypeGuard<TType>;
+}
+export function create<TType = any>(
+  spec?: MixedOptions<TType> | TypeGuard<TType>,
+) {
+  return new MixedSchema<TType | undefined>(spec);
+}
+
+export default class MixedSchema<
+  TType = any,
+  TContext = AnyObject,
+  TDefault = undefined,
+  TFlags extends Flags = '',
+> extends Schema<TType, TContext, TDefault, TFlags> {
+  constructor(spec?: MixedOptions<TType> | TypeGuard<TType>) {
+    super(
+      typeof spec === 'function'
+        ? { type: 'mixed', check: spec }
+        : { type: 'mixed', check: returnsTrue as TypeGuard<TType>, ...spec },
+    );
+  }
+}
+
+export default interface MixedSchema<
   TType = any,
   TContext = AnyObject,
   TDefault = undefined,
   TFlags extends Flags = '',
-> extends BaseSchema<TType, TContext, TDefault, TFlags> {
+> extends Schema<TType, TContext, TDefault, TFlags> {
   default<D extends Maybe<TType>>(
     def: Thunk<D>,
   ): MixedSchema<TType, TContext, D, ToggleDefault<TFlags, D>>;
@@ -24,7 +52,7 @@ export declare class MixedSchema<
     schema: MixedSchema<IT, IC, ID, IF>,
   ): MixedSchema<Concat<TType, IT>, TContext & IC, ID, TFlags | IF>;
   concat<IT, IC, ID, IF extends Flags>(
-    schema: BaseSchema<IT, IC, ID, IF>,
+    schema: Schema<IT, IC, ID, IF>,
   ): MixedSchema<Concat<TType, IT>, TContext & IC, ID, TFlags | IF>;
   concat(schema: this): this;
 
@@ -52,21 +80,4 @@ export declare class MixedSchema<
   ): MixedSchema<TType, TContext, TDefault, SetFlag<TFlags, 's'>>;
 }
 
-const Mixed: typeof MixedSchema = BaseSchema as any;
-
-export default Mixed;
-
-export type TypeGuard<TType> = (value: any) => value is NonNullable<TType>;
-export interface MixedOptions<TType> {
-  type?: string;
-  check?: TypeGuard<TType>;
-}
-export function create<TType = any>(
-  spec?: MixedOptions<TType> | TypeGuard<TType>,
-) {
-  return new Mixed<TType | undefined>(
-    typeof spec === 'function' ? { check: spec } : spec,
-  );
-}
-// XXX: this is using the Base schema so that `addMethod(mixed)` works as a base class
-create.prototype = Mixed.prototype;
+create.prototype = MixedSchema.prototype;

src/number.ts

@@ -12,7 +12,7 @@ import type {
   ToggleDefault,
   UnsetFlag,
 } from './util/types';
-import BaseSchema from './schema';
+import Schema from './schema';
 
 let isNaN = (value: Maybe<number>) => value != +value!;
 
@@ -30,7 +30,7 @@ export default class NumberSchema<
   TContext = AnyObject,
   TDefault = undefined,
   TFlags extends Flags = '',
-> extends BaseSchema<TType, TContext, TDefault, TFlags> {
+> extends Schema<TType, TContext, TDefault, TFlags> {
   constructor() {
     super({
       type: 'number',
@@ -156,7 +156,7 @@ export default interface NumberSchema<
   TContext = AnyObject,
   TDefault = undefined,
   TFlags extends Flags = '',
-> extends BaseSchema<TType, TContext, TDefault, TFlags> {
+> extends Schema<TType, TContext, TDefault, TFlags> {
   default<D extends Maybe<TType>>(
     def: Thunk<D>,
   ): NumberSchema<TType, TContext, D, ToggleDefault<TFlags, D>>;

src/object.ts

@@ -17,7 +17,7 @@ import { InternalOptions, Callback, Maybe, Message } from './types';
 import ValidationError from './ValidationError';
 import type { Defined, Thunk, NotNull, _ } from './util/types';
 import type Reference from './Reference';
-import BaseSchema, { SchemaObjectDescription, SchemaSpec } from './schema';
+import Schema, { SchemaObjectDescription, SchemaSpec } from './schema';
 import { ResolveOptions } from './Condition';
 import type {
   AnyObject,
@@ -74,7 +74,7 @@ export default interface ObjectSchema<
   // will match object schema regardless of defaults
   TDefault = any,
   TFlags extends Flags = '',
-> extends BaseSchema<MakeKeysOptional<TIn>, TContext, TDefault, TFlags> {
+> extends Schema<MakeKeysOptional<TIn>, TContext, TDefault, TFlags> {
   default<D extends Maybe<AnyObject>>(
     def: Thunk<D>,
   ): ObjectSchema<TIn, TContext, D, ToggleDefault<TFlags, 'd'>>;
@@ -105,7 +105,7 @@ export default class ObjectSchema<
   TContext = AnyObject,
   TDefault = any,
   TFlags extends Flags = '',
-> extends BaseSchema<MakeKeysOptional<TIn>, TContext, TDefault, TFlags> {
+> extends Schema<MakeKeysOptional<TIn>, TContext, TDefault, TFlags> {
   fields: Shape<NonNullable<TIn>, TContext> = Object.create(null);
 
   declare spec: ObjectSchemaSpec;
@@ -184,7 +184,7 @@ export default class ObjectSchema<
           parent: intermediateValue,
         });
 
-        let fieldSpec = field instanceof BaseSchema ? field.spec : undefined;
+        let fieldSpec = field instanceof Schema ? field.spec : undefined;
         let strict = fieldSpec?.strict;
 
         if (fieldSpec?.strip) {
@@ -391,7 +391,7 @@ export default class ObjectSchema<
   partial() {
     const partial: any = {};
     for (const [key, schema] of Object.entries(this.fields)) {
-      partial[key] = schema instanceof BaseSchema ? schema.optional() : schema;
+      partial[key] = schema instanceof Schema ? schema.optional() : schema;
     }
 
     return this.setFields<Partial<TIn>, TDefault>(partial);
@@ -401,9 +401,7 @@ export default class ObjectSchema<
     const partial: any = {};
     for (const [key, schema] of Object.entries(this.fields)) {
       if (schema instanceof ObjectSchema) partial[key] = schema.deepPartial();
-      else
-        partial[key] =
-          schema instanceof BaseSchema ? schema.optional() : schema;
+      else partial[key] = schema instanceof Schema ? schema.optional() : schema;
     }
     return this.setFields<PartialDeep<TIn>, TDefault>(partial);
   }