Addon-knobs: improve types via generics and readonlyarray

addons/knobs/src/KnobManager.ts

@@ -7,7 +7,7 @@ import { getQueryParams } from '@storybook/client-api';
 import { Channel } from '@storybook/channels';
 
 import KnobStore, { KnobStoreKnob } from './KnobStore';
-import { Knob, KnobType } from './type-defs';
+import { Knob, KnobType, Mutable } from './type-defs';
 import { SET } from './shared';
 
 import { deserializers } from './converters';
@@ -72,7 +72,7 @@ export default class KnobManager {
     return this.options.escapeHTML ? escapeStrings(value) : value;
   }
 
-  knob<T extends KnobType = any>(name: string, options: Knob<T>): Knob<T>['value'] {
+  knob<T extends KnobType = any>(name: string, options: Knob<T>): Mutable<Knob<T>['value']> {
     this._mayCallChannel();
 
     const knobName = options.groupId ? `${name}_${options.groupId}` : name;

addons/knobs/src/__types__/knob-test-cases.ts

@@ -0,0 +1,204 @@
+import {
+  number,
+  color,
+  files,
+  object,
+  boolean,
+  text,
+  select,
+  date,
+  array,
+  button,
+  knob,
+  radios,
+  optionsKnob as options,
+} from '../index';
+
+// Note: this is a helper to batch test return types and avoid "declared but never read" errors
+function expectKnobOfType<T>(..._: T[]) {}
+
+const groupId = 'GROUP-ID1';
+
+/** Text knob */
+
+expectKnobOfType<string>(
+  text('text simple', 'Batman'),
+  text('text with group', 'default', groupId)
+);
+
+/** Date knob */
+
+expectKnobOfType<number>(
+  date('date simple', new Date('January 20 1887')),
+  date('date with group', new Date(), groupId)
+);
+
+/** Boolean knob */
+
+expectKnobOfType<boolean>(
+  boolean('boolean simple', false),
+  boolean('boolean with group', true, groupId)
+);
+
+/** Color knob */
+
+expectKnobOfType<string>(
+  color('color simple', 'black'),
+  color('color with group', '#ffffff', groupId)
+);
+
+/** Number knob */
+
+expectKnobOfType<number>(
+  number('number basic', 42),
+  number('number with options', 72, { range: true, min: 60, max: 90, step: 1 }),
+  number('number with group', 1, {}, groupId)
+);
+
+/** Radios knob */
+
+expectKnobOfType(
+  radios<string>(
+    'radio with string values',
+    {
+      1100: '1100',
+      2200: '2200',
+      3300: '3300',
+    },
+    '2200'
+  ),
+  radios<number>('radio with number values', { 3: 3, 7: 7, 23: 23 }, 3),
+  radios(
+    'radio with mixed value',
+    {
+      1100: '1100',
+      2200: 2200,
+      3300: '3300',
+    },
+    null,
+    groupId
+  )
+);
+
+/** Select knob */
+
+enum SomeEnum {
+  Type1 = 1,
+  Type2,
+}
+enum ButtonVariant {
+  primary = 'primary',
+  secondary = 'secondary',
+}
+const stringLiteralArray: ('Apple' | 'Banana' | 'Grapes')[] = ['Apple', 'Banana', 'Grapes'];
+
+expectKnobOfType<string>(
+  select(
+    'select with string options',
+    {
+      None: 'none',
+      Underline: 'underline',
+      'Line-through': 'line-through',
+    },
+    'none'
+  ),
+  select('select with string array', ['yes', 'no'], 'yes'),
+  select('select with string literal array', stringLiteralArray, stringLiteralArray[0]),
+  select('select with readonly array', ['red', 'blue'] as const, 'red'),
+  select<ButtonVariant>('select with string enum options', ButtonVariant, ButtonVariant.primary),
+  select('select with null option', { a: 'Option', b: null }, null, groupId)
+);
+
+expectKnobOfType<number>(
+  select('select with number options', { 'type a': 1, 'type b': 2 }, 1),
+  select<SomeEnum>(
+    'select with numeric enum options',
+    { 'type a': SomeEnum.Type1, 'type b': SomeEnum.Type2 },
+    SomeEnum.Type2
+  ),
+  select('select with number array', [1, 2, 3, 4], 1),
+  select('select with readonly number array', [1, 2] as const, 1)
+);
+
+/** Object knob */
+
+expectKnobOfType(
+  object('object simple', {
+    fontFamily: 'Arial',
+    padding: 20,
+  }),
+  object('object with group', {}, groupId)
+);
+
+/** Options knob */
+
+type Tool = 'hammer' | 'saw' | 'drill';
+const visibleToolOptions: Record<string, Tool> = {
+  hammer: 'hammer',
+  saw: 'saw',
+  drill: 'drill',
+};
+
+expectKnobOfType(
+  options<Tool>('options with single selection', visibleToolOptions, 'hammer', {
+    display: 'check',
+  }),
+  options<Tool>('options with multi selection', visibleToolOptions, ['hammer', 'saw'], {
+    display: 'inline-check',
+  }),
+  options<Tool>('options with readonly multi selection', visibleToolOptions, ['hammer'] as const, {
+    display: 'radio',
+  }),
+  options('options with group', {}, '', { display: 'check' })
+);
+
+/** Array knob */
+
+const arrayReadonly = array('array as readonly', ['hi', 'there'] as const);
+
+expectKnobOfType<string[]>(
+  array('array simple', ['red', 'green', 'blue']),
+  arrayReadonly,
+  array('array with group', [], ',', groupId)
+);
+
+// Should return a mutable array despite the readonly input
+arrayReadonly.push('Make sure that the output is still mutable although the input need not be!');
+
+/** Button knob */
+
+expectKnobOfType(
+  button('button simple', () => {}),
+  button('button with group', () => undefined, groupId)
+);
+
+/** Files knob */
+
+expectKnobOfType<string[]>(
+  files('files simple', 'image/*', []),
+  files('files with group', 'image/*', ['img.jpg'], groupId)
+);
+
+/** Generic knob */
+
+expectKnobOfType<string>(
+  knob('generic knob as text', { type: 'text', value: 'a' }),
+  knob('generic knob as color', { type: 'color', value: 'black' }),
+  knob<'select', string>('generic knob as string select', {
+    type: 'select',
+    value: 'yes',
+    options: ['yes', 'no'],
+    selectV2: true,
+  })
+);
+
+expectKnobOfType<number>(
+  knob('generic knob as number', { type: 'number', value: 42 }),
+  knob('generic knob as select', { type: 'radios', value: 3, options: { 3: 3, 7: 7, 23: 23 } }),
+  knob('generic knob as number select', {
+    type: 'select',
+    value: 1,
+    options: [1, 2],
+    selectV2: true,
+  })
+);

addons/knobs/src/components/types/Array.tsx

@@ -2,18 +2,16 @@ import PropTypes from 'prop-types';
 import React, { ChangeEvent, Component, WeakValidationMap } from 'react';
 
 import { Form } from '@storybook/components';
+import { KnobControlConfig, KnobControlProps } from './types';
 
-type ArrayTypeKnobValue = string[];
+export type ArrayTypeKnobValue = string[] | readonly string[];
 
-export interface ArrayTypeKnob {
-  name: string;
-  value: ArrayTypeKnobValue;
+export interface ArrayTypeKnob extends KnobControlConfig<ArrayTypeKnobValue> {
   separator: string;
 }
 
-interface ArrayTypeProps {
+interface ArrayTypeProps extends KnobControlProps<ArrayTypeKnobValue> {
   knob: ArrayTypeKnob;
-  onChange: (value: ArrayTypeKnobValue) => ArrayTypeKnobValue;
 }
 
 function formatArray(value: string, separator: string) {
@@ -41,7 +39,7 @@ export default class ArrayType extends Component<ArrayTypeProps> {
 
   static serialize = (value: ArrayTypeKnobValue) => value;
 
-  static deserialize = (value: ArrayTypeKnobValue) => {
+  static deserialize = (value: string[]) => {
     if (Array.isArray(value)) return value;
 
     return Object.keys(value)

addons/knobs/src/components/types/Boolean.tsx

@@ -2,18 +2,14 @@ import PropTypes from 'prop-types';
 import React, { FunctionComponent } from 'react';
 
 import { styled } from '@storybook/theming';
+import { KnobControlConfig, KnobControlProps } from './types';
 
 type BooleanTypeKnobValue = boolean;
 
-export interface BooleanTypeKnob {
-  name: string;
-  value: BooleanTypeKnobValue;
-  separator: string;
-}
+export type BooleanTypeKnob = KnobControlConfig<BooleanTypeKnobValue>;
 
-export interface BooleanTypeProps {
+export interface BooleanTypeProps extends KnobControlProps<BooleanTypeKnobValue> {
   knob: BooleanTypeKnob;
-  onChange: (value: BooleanTypeKnobValue) => BooleanTypeKnobValue;
 }
 
 const Input = styled.input({

addons/knobs/src/components/types/Button.tsx

@@ -2,19 +2,17 @@ import PropTypes from 'prop-types';
 import React, { FunctionComponent, Validator } from 'react';
 
 import { Form } from '@storybook/components';
+import { KnobControlConfig, KnobControlProps } from './types';
 
-export interface ButtonTypeKnob {
-  name: string;
-  value: unknown;
-}
-
-export type ButtonTypeOnClickProp = (knob: ButtonTypeKnob) => any;
+export type ButtonTypeKnob = KnobControlConfig<never>;
 
-export interface ButtonTypeProps {
+export interface ButtonTypeProps extends KnobControlProps<never> {
   knob: ButtonTypeKnob;
   onClick: ButtonTypeOnClickProp;
 }
 
+export type ButtonTypeOnClickProp = (knob: ButtonTypeKnob) => any;
+
 const serialize = (): undefined => undefined;
 const deserialize = (): undefined => undefined;
 

addons/knobs/src/components/types/Checkboxes.tsx

@@ -1,32 +1,28 @@
 import React, { Component, ChangeEvent, WeakValidationMap } from 'react';
 import PropTypes from 'prop-types';
 import { styled } from '@storybook/theming';
+import { KnobControlConfig, KnobControlProps } from './types';
 
 type CheckboxesTypeKnobValue = string[];
 
-interface CheckboxesWrapperProps {
-  isInline: boolean;
-}
-
-export interface CheckboxesTypeKnob {
-  name: string;
-  value: CheckboxesTypeKnobValue;
-  defaultValue: CheckboxesTypeKnobValue;
-  options: {
-    [key: string]: string;
-  };
+export interface CheckboxesTypeKnob extends KnobControlConfig<CheckboxesTypeKnobValue> {
+  options: Record<string, string>;
 }
 
-interface CheckboxesTypeProps {
+interface CheckboxesTypeProps
+  extends KnobControlProps<CheckboxesTypeKnobValue>,
+    CheckboxesWrapperProps {
   knob: CheckboxesTypeKnob;
-  isInline: boolean;
-  onChange: (value: CheckboxesTypeKnobValue) => CheckboxesTypeKnobValue;
 }
 
 interface CheckboxesTypeState {
   values: CheckboxesTypeKnobValue;
 }
 
+interface CheckboxesWrapperProps {
+  isInline: boolean;
+}
+
 const CheckboxesWrapper = styled.div(({ isInline }: CheckboxesWrapperProps) =>
   isInline
     ? {

addons/knobs/src/components/types/Color.tsx

@@ -5,18 +5,11 @@ import { SketchPicker, ColorResult } from 'react-color';
 
 import { styled } from '@storybook/theming';
 import { Form } from '@storybook/components';
+import { KnobControlConfig, KnobControlProps } from './types';
 
 type ColorTypeKnobValue = string;
-
-export interface ColorTypeKnob {
-  name: string;
-  value: ColorTypeKnobValue;
-}
-
-interface ColorTypeProps {
-  knob: ColorTypeKnob;
-  onChange: (value: ColorTypeKnobValue) => ColorTypeKnobValue;
-}
+export type ColorTypeKnob = KnobControlConfig<ColorTypeKnobValue>;
+type ColorTypeProps = KnobControlProps<ColorTypeKnobValue>;
 
 interface ColorTypeState {
   displayColorPicker: boolean;

addons/knobs/src/components/types/Date.tsx

@@ -2,18 +2,11 @@ import React, { Component, ChangeEvent, WeakValidationMap } from 'react';
 import PropTypes from 'prop-types';
 import { styled } from '@storybook/theming';
 import { Form } from '@storybook/components';
+import { KnobControlConfig, KnobControlProps } from './types';
 
 type DateTypeKnobValue = number;
-
-export interface DateTypeKnob {
-  name: string;
-  value: DateTypeKnobValue;
-}
-
-interface DateTypeProps {
-  knob: DateTypeKnob;
-  onChange: (value: DateTypeKnobValue) => DateTypeKnobValue;
-}
+export type DateTypeKnob = KnobControlConfig<DateTypeKnobValue>;
+type DateTypeProps = KnobControlProps<DateTypeKnobValue>;
 
 interface DateTypeState {
   valid: boolean | undefined;