Merge 7722664 into 6acd314

CHANGELOG.md

@@ -4,4 +4,4 @@
 ### Features
 
 * Implement `withWhenConnected` ([cabd37a](https://github.com/leofavre/elmnt/commit/cabd37a))
-* Implement withElmnt ([87911d8](https://github.com/leofavre/elmnt/commit/87911d8))
+* Implement `withElmnt` ([87911d8](https://github.com/leofavre/elmnt/commit/87911d8))

src/decorators/withSetState.js

@@ -0,0 +1,10 @@
+import isFunction from '../helpers/isFunction.js';
+
+export default (Base = class {}) => class extends Base {
+  setState (arg) {
+    this.state = {
+      ...(this.state || {}),
+      ...(isFunction(arg) ? arg(this.state) : arg)
+    };
+  }
+};

src/decorators/withSetState.spec.js

@@ -0,0 +1,43 @@
+import withSetState from './withSetState.js';
+
+class Dummy extends withSetState() {}
+
+describe('withSetState', () => {
+  it('Should extend this.state with new properties ' +
+    'if called with an object.', () => {
+    const dummy = new Dummy();
+    dummy.state = { level: 42 };
+    dummy.setState({ ub: 40 });
+    expect(dummy.state).to.deep.equal({ level: 42, ub: 40 });
+  });
+
+  it('Should override properties with the same name.', () => {
+    const dummy = new Dummy();
+    dummy.state = { level: 42 };
+    dummy.setState({ level: 202 });
+    expect(dummy.state).to.deep.equal({ level: 202 });
+  });
+
+  it('Should extend this.state with new properties ' +
+    'if called with a function that returns an object.', () => {
+    const dummy = new Dummy();
+    dummy.state = { level: 42 };
+    dummy.setState(() => ({ ub: 40 }));
+    expect(dummy.state).to.deep.equal({ level: 42, ub: 40 });
+  });
+
+  it('Should expose this.state’s previous value ' +
+    'if called with a function that returns an object.', () => {
+    const dummy = new Dummy();
+    dummy.state = { level: 42 };
+    dummy.setState(prevState => ({ level: prevState.level + 1 }));
+    expect(dummy.state).to.deep.equal({ level: 43 });
+  });
+
+  it('Should initialize this.state with an empty object ' +
+    'if not set.', () => {
+    const dummy = new Dummy();
+    dummy.setState({ ub: 40 });
+    expect(dummy.state).to.deep.equal({ ub: 40 });
+  });
+});

src/index.js

@@ -1,4 +1,5 @@
 import withElmnt from './decorators/withElmnt.js';
+import withSetState from './decorators/withSetState.js';
 
 import coerceToArray from './coercion/coerceToArray.js';
 import coerceToArrayOrUndefined from './coercion/coerceToArrayOrUndefined.js';
@@ -10,6 +11,7 @@ import coerceToStringOrUndefined from './coercion/coerceToStringOrUndefined.js';
 
 export {
   withElmnt,
+  withSetState,
   coerceToArray,
   coerceToArrayOrUndefined,
   coerceToBoolean,