More tests and license

LICENSE.md

@@ -0,0 +1,21 @@
+MIT License
+
+Copyright (c) 2017 Jakob Nilsson-Ehle
+
+Permission is hereby granted, free of charge, to any person obtaining a copy
+of this software and associated documentation files (the "Software"), to deal
+in the Software without restriction, including without limitation the rights
+to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+copies of the Software, and to permit persons to whom the Software is
+furnished to do so, subject to the following conditions:
+
+The above copyright notice and this permission notice shall be included in all
+copies or substantial portions of the Software.
+
+THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+SOFTWARE.

README.md

@@ -167,3 +167,7 @@ const reducer = chain([
 
 reducer(1, {value: 1, type: "SUBTRACT_VALUE"}) //1
 reducer(1, {value: 2, type: "ADD_VALUE"}) //3
+
+
+## license
+See [LICENSE.md]

src/merge-states.js

@@ -1,21 +1,23 @@
 import isPlainObject from 'is-plain-object';
 import assign from 'object-assign';
 
-const merge = (reducer) => {
+const mergeStates = (reducer) => {
   if (typeof reducer !== 'function') {
     throw new Error('Argument supplied to `merge` is not a reducer');
   }
 
   return (state, action) => {
     if (!isPlainObject(state)) {
-      throw new Error('`merge` only works with plain object states');
+      const type = typeof state;
+      throw new Error(`"mergeStates" only works with plain object states, but got a "${type}"`);
     }
     const nextState = reducer(state, action);
     if (!isPlainObject(nextState)) {
-      throw new Error('The reducer in `merge` did not return a plain object');
+      const type = typeof nextState;
+      throw new Error(`The reducer in "mergeStates" did not return a plain object. Instead it was a "${type}"`);
     }
     return assign({}, state, nextState);
   };
 };
 
-export default merge;
+export default mergeStates;

test/always.spec.js

@@ -1,7 +1,7 @@
 import sinon from 'sinon';
 import chai, { expect } from 'chai';
 import sinonChai from 'sinon-chai';
-import always from '../lib/always';
+import { always } from '../lib';
 
 chai.use(sinonChai);
 

test/chain.spec.js

@@ -1,7 +1,7 @@
 import sinon from 'sinon';
 import chai, { expect } from 'chai';
 import sinonChai from 'sinon-chai';
-import chain from '../lib/chain';
+import { chain } from '../lib';
 
 chai.use(sinonChai);
 

test/merge-states.spec.js

@@ -0,0 +1,41 @@
+import sinon from 'sinon';
+import chai, { expect } from 'chai';
+import sinonChai from 'sinon-chai';
+import { mergeStates } from '../lib';
+
+chai.use(sinonChai);
+
+describe('mergeStates', () => {
+  it('throws an error if the inner reducer is not an object', () => {
+    expect(() => mergeStates()).to.throw('not a reducer');
+    expect(() => mergeStates(null)).to.throw('not a reducer');
+    expect(() => mergeStates(1)).to.throw('not a reducer');
+    expect(() => mergeStates(new Date())).to.throw('not a reducer');
+    expect(() => mergeStates({})).to.throw('not a reducer');
+  });
+
+  it('does not throw if the inner reducer is a function', () => {
+    expect(() => mergeStates(() => {})).to.not.throw;
+  });
+
+  it('throws an error if the supplied state is not an object', () => {
+    const reducer = mergeStates(() => {});
+    expect(() => reducer()).to.throw('"mergeStates" only works with plain object states');
+    expect(() => reducer(null)).to.throw('"mergeStates" only works with plain object states');
+    expect(() => reducer(1)).to.throw('"mergeStates" only works with plain object states');
+    expect(() => reducer(() => {})).to.throw('"mergeStates" only works with plain object states');
+    expect(() => reducer(new Date())).to.throw('"mergeStates" only works with plain object states');
+  });
+
+  it('does not throw errors it the state is an object', () => {
+    const reducer = mergeStates(() => {});
+    expect(() => reducer({})).to.not.throw('"mergeStates" only works with plain object states');
+  });
+
+  it('calls the inner reducer', () => {
+    const innerReducer = sinon.stub().returns({});
+    const reducer = mergeStates(innerReducer);
+    reducer({});
+    expect(innerReducer).to.have.been.calledOnce;
+  });
+});