TASK: Implement connection

src/connections/atoms/and/index.js

@@ -0,0 +1,15 @@
+const reduceOps = ops => subject => ops.reduce(
+    (subject, nextOp) => subject === false ? subject : nextOp(subject),
+    subject
+);
+
+//
+// Performs all passed operations until one of them returns false
+//
+export default (...ops) => {
+    if (typeof ops[ops.length - 1] !== 'function') {
+        return reduceOps(ops.slice(0, -1))(ops[ops.length - 1]);
+    }
+
+    return reduceOps(ops);
+};

src/connections/atoms/and/index.spec.js

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+import {expect} from 'chai';
+import sinon from 'sinon';
+
+import $and from './index.js';
+
+describe('Connections > Atoms > $and', () => {
+    // Helper Identity function
+    const id = id => id;
+
+    describe('Common', () => {
+        it('$and :: ...Function -> Object -> *', () => {
+            expect($and).to.be.a('function');
+            expect($and(() => {})).to.be.a('function');
+            expect($and(() => {}, () => {})).to.be.a('function');
+            expect($and(() => {}, () => {}, () => {})).to.be.a('function');
+            expect($and(() => {})({})).not.to.be.a('function');
+            expect($and(() => {}, () => {})({})).not.to.be.a('function');
+            expect($and(() => {}, () => {}, () => {})({})).not.to.be.a('function');
+        });
+
+        it('$and :: (...Function, Object) -> *', () => {
+            expect($and(() => {}, {})).not.to.be.a('function');
+            expect($and(() => {}, () => {}, {})).not.to.be.a('function');
+            expect($and(() => {}, () => {}, () => {}, {})).not.to.be.a('function');
+            expect($and(() => {}, () => {}, () => {}, () => {}, {})).not.to.be.a('function');
+        });
+    });
+
+    describe('Vanilla JS', () => {
+        it('should call all passed functions with the passed subject', () => {
+            const subject = 'mySubject';
+            const op1 = sinon.spy(id);
+            const op2 = sinon.spy(id);
+            const op3 = sinon.spy(id);
+
+            expect($and(op1, op2, op3, subject)).to.equal('mySubject');
+            expect(op1.called).to.equal(true);
+            expect(op1.getCall(0).args[0]).to.equal('mySubject');
+            expect(op2.called).to.equal(true);
+            expect(op2.getCall(0).args[0]).to.equal('mySubject');
+            expect(op3.called).to.equal(true);
+            expect(op3.getCall(0).args[0]).to.equal('mySubject');
+        });
+
+        it('should call the passed functions in a predictable order', () => {
+            const subject = 1;
+            const op1 = sinon.spy(a => a + 1);
+            const op2 = sinon.spy(a => a + 2);
+            const op3 = sinon.spy(a => a + 3);
+
+            expect($and(op1, op2, op3, subject)).to.equal(7);
+            expect($and(op3, op2, op1, subject)).to.equal(7);
+
+            expect(op1.getCall(0).args[0]).to.equal(1);
+            expect(op1.getCall(1).args[0]).to.equal(6);
+            expect(op2.getCall(0).args[0]).to.equal(2);
+            expect(op2.getCall(1).args[0]).to.equal(4);
+            expect(op3.getCall(0).args[0]).to.equal(4);
+            expect(op3.getCall(1).args[0]).to.equal(1);
+        });
+
+        it('should return false, if any of the functions returns false', () => {
+            const subject = 'mySubject';
+            const opTrue = () => true;
+            const opFalse = () => false;
+
+            expect($and(opTrue, opTrue, opTrue, opTrue, subject)).to.equal(true);
+            expect($and(opFalse, opTrue, opTrue, opTrue, subject)).to.equal(false);
+            expect($and(opTrue, opFalse, opTrue, opTrue, subject)).to.equal(false);
+            expect($and(opTrue, opTrue, opFalse, opTrue, subject)).to.equal(false);
+            expect($and(opTrue, opTrue, opTrue, opFalse, subject)).to.equal(false);
+        });
+    });
+});