Fixes and tests

Author: minajevs

.gitignore

@@ -1,4 +1,5 @@
 node_modules
 dist
+coverage
 *.lock
 *.log

.travis.yml

@@ -0,0 +1,12 @@
+language: node_js
+branches:
+  only:
+  - master
+cache:
+  directories:
+  - node_modules
+install:
+- npm install
+script:
+- npm test
+- npm run coverage

package.json

@@ -12,7 +12,9 @@
   ],
   "scripts": {
     "build": "tsc -p .",
-    "test": "exit 0"
+    "test": "./node_modules/.bin/jest --collectCoverage",
+    "test:watch": "./node_modules/.bin/jest --watch",
+    "coverage": "./node_modules/.bin/codecov"
   },
   "keywords": [
     "react",
@@ -22,9 +24,43 @@
   ],
   "license": "MIT",
   "dependencies": {},
+  "peerDependencies": {
+    "react": ">=16.3.0"
+  },
   "devDependencies": {
+    "@types/enzyme": "^3.9.0",
+    "@types/enzyme-adapter-react-16": "^1.0.5",
+    "@types/jest": "^24.0.11",
     "@types/react": "^16.8.8",
+    "codecov": "^3.2.0",
+    "enzyme": "^3.9.0",
+    "enzyme-adapter-react-16": "^1.11.2",
+    "enzyme-to-json": "^3.3.5",
+    "jest": "^24.5.0",
+    "raf": "^3.4.1",
     "react": "^16.8.4",
+    "react-dom": "^16.8.4",
+    "ts-jest": "^24.0.0",
     "typescript": "^3.3.3333"
+  },
+  "jest": {
+    "moduleFileExtensions": [
+      "ts",
+      "tsx",
+      "js"
+    ],
+    "transform": {
+      "\\.(ts|tsx)$": "ts-jest"
+    },
+    "setupFiles": [
+      "raf/polyfill"
+    ],
+    "testRegex": "/tests/.*\\.(ts|tsx|js)$",
+    "setupFilesAfterEnv": [
+      "<rootDir>/setupTests.ts"
+    ],
+    "snapshotSerializers": [
+      "enzyme-to-json"
+    ]
   }
 }

setupTests.ts

@@ -0,0 +1,6 @@
+import * as Enzyme from 'enzyme'
+import * as Adapter from 'enzyme-adapter-react-16'
+
+Enzyme.configure({
+    adapter: new Adapter(),
+})

src/helperTypes.ts

@@ -1,18 +1,50 @@
 import * as React from 'react'
-import { Params, DropFirst } from 'src/helperTypes'
 
-type Action<TState, TArgs extends any[]= any, TReturn = void> =
-    (setState: React.Dispatch<React.SetStateAction<TState>>, ...args: TArgs) => TReturn
+/*
+    Custom Helper types
+*/
+
+// Custom Params helper type because existing counterpart "Parameters" uses any instead of never, which is faulsy
+export type Params<T extends (...args: never[]) => unknown> = T extends (...args: infer P) => any ? P : never;
+
+// Custom RetType helper type because existing counterpart "ReturnType" uses any instead of never, which is faulsy
+export type RetType<T extends (...args: never[]) => unknown> = T extends (...args: never[]) => infer R ? R : any;
+
+// For [First, ...Rest] tuple gets [Rest] tuple
+export type DropFirst<T extends any[]> =
+    ((...args: T) => any) extends (arg: any, ...rest: infer U) => any[] ? U : T;
+
+export type Tail<T> = T extends Array<any>
+    ? ((...args: T) => never) extends ((a: any, ...args: infer R) => never)
+    ? R
+    : never
+    : never
+
+/*
+    API Types
+*/
+
+type ContextReference<TState> = {
+    setState: React.Dispatch<React.SetStateAction<TState>>
+    useContext: <T>(context: React.Context<T>) => T
+}
+
+type Action<TState, TArgs extends never[]= never[], TReturn = any> =
+    (contextReference: ContextReference<TState>, ...args: TArgs) => TReturn
 
 type Actions<TState> = { [key: string]: Action<TState> }
 
 type MappedActions<TState, TActions extends Actions<TState>> = {
-    [P in keyof TActions]: (...args: DropFirst<Params<TActions[P]>>) => ReturnType<TActions[P]>
+    [P in keyof TActions]: (...args: DropFirst<Params<TActions[P]>>) => RetType<TActions[P]>
 }
 
 type Store<TState, TActions extends Actions<TState>> =
     TActions extends undefined ? TState : TState & MappedActions<TState, TActions>
 
+/*
+    Logic
+*/
+
 export default function createStateContext<TState, TActions extends Actions<TState> = {}>(
     initialState: TState,
     actions?: TActions
@@ -22,8 +54,11 @@ export default function createStateContext<TState, TActions extends Actions<TSta
 
     const provider: React.FC = props => {
         let [_state, setState] = React.useState(initialState)
-
-        const _actions = mapActionsToDispatch(setState, actions)
+        const useContext = React.useContext
+        const _actions = mapActionsToDispatch({
+            setState,
+            useContext
+        }, actions)
 
         const _store = { ..._state, ..._actions } as Store<TState, TActions>
 
@@ -38,15 +73,16 @@ export default function createStateContext<TState, TActions extends Actions<TSta
 }
 
 function mapActionsToDispatch<TState, TActions extends Actions<TState>>(
-    dispatch: React.Dispatch<React.SetStateAction<TState>>,
+    contextReference: ContextReference<TState>,
     actions?: TActions,
 ): MappedActions<TState, TActions> {
     if (actions === undefined) return {} as MappedActions<TState, TActions>
     return Object.keys(actions).reduce(
         (obj, key) => {
+            const action = actions[key]
             return {
                 ...obj,
-                [key]: (...payload: never[]) => actions[key](dispatch, payload[0])
+                [key]: (...args: never[]) => actions[key](contextReference, ...args)
             }
         },
         {} as MappedActions<TState, TActions>)
@@ -60,8 +96,7 @@ function mapActionsToDefault<TState, TActions extends Actions<TState>>(
         (obj, key) => {
             return {
                 ...obj,
-                [key]: (...payload: never[]) =>
-                    () => { throw new Error(`Can't invoke ${key} because provider does not exist`) }
+                [key]: (...args: never[]) => { throw new Error(`Can't invoke ${key} because provider does not exist`) }
             }
         },
         {} as MappedActions<TState, TActions>)