4 passing

orderbook.js

@@ -0,0 +1,158 @@
+describe('15', () => {
+     describe('reconcileOrder', () => {
+       it('adds an order to the book when the book is empty and thus cannot fulfill the order', () => {
+         const existingBook = []
+         const incomingOrder = { type: 'sell', quantity: 10, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 10, price: 6150 }])
+       })
+
+       it('adds an order to the book when the book has orders of the corresponding type (i.e. a sell with no buys)', () => {
+         const existingBook = [{ type: 'sell', quantity: 10, price: 6150 }]
+         const incomingOrder = { type: 'sell', quantity: 12, price: 6000 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([
+           { type: 'sell', quantity: 10, price: 6150 },
+           { type: 'sell', quantity: 12, price: 6000 }
+         ])
+       })
+
+       it('adds an order to the book when the book has a corresponding order type but it does not match', () => {
+         const existingBook = [{ type: 'buy', quantity: 10, price: 6000 }]
+         const incomingOrder = { type: 'sell', quantity: 12, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([
+           { type: 'buy', quantity: 10, price: 6000 },
+           { type: 'sell', quantity: 12, price: 6150 }
+         ])
+       })
+
+       it('fulfills an order and removes the matching order when the book contains a matching order of the same quantity', () => {
+         const existingBook = [{ type: 'buy', quantity: 10, price: 6150 }, { type: 'sell', quantity: 12, price: 6250 }]
+         const incomingOrder = { type: 'sell', quantity: 10, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 6250 }])
+       })
+
+       it('fulfills an order and reduces the matching order when the book contains a matching order of a larger quantity', () => {
+         const existingBook = [{ type: 'buy', quantity: 15, price: 6150 }, { type: 'sell', quantity: 12, price: 6950 }]
+         const incomingOrder = { type: 'sell', quantity: 10, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 6950 }, { type: 'buy', quantity: 5, price: 6150 }])
+       })
+
+       it('partially fulfills an order, removes the matching order and adds the remainder of the order to the book when the book contains a matching order of a smaller quantity', () => {
+         const existingBook = [{ type: 'buy', quantity: 10, price: 6150 }, { type: 'sell', quantity: 12, price: 5950 }]
+         const incomingOrder = { type: 'sell', quantity: 15, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 5950 }, { type: 'sell', quantity: 5, price: 6150 }])
+       })
+
+       it('uses two existing orders to completely fulfill an order, removing the matching orders from the book', () => {
+         const existingBook = [{ type: 'buy', quantity: 10, price: 6150 }, { type: 'buy', quantity: 5, price: 6150 }, { type: 'sell', quantity: 12, price: 5950 }]
+         const incomingOrder = { type: 'sell', quantity: 15, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 5950 }])
+       })
+
+       it('uses two existing orders to completely fulfill an order, removing the first matching order from the book and reducing the second', () => {
+         const existingBook = [{ type: 'buy', quantity: 10, price: 6150 }, { type: 'buy', quantity: 10, price: 6150 }, { type: 'sell', quantity: 12, price: 6950 }]
+         const incomingOrder = { type: 'sell', quantity: 15, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 6950 }, { type: 'buy', quantity: 5, price: 6150 }])
+       })
+
+       it('uses two existing orders to partially fulfill an order, removing the matching orders from the book and reducing the incoming order before adding it to the book', () => {
+         const existingBook = [{ type: 'buy', quantity: 10, price: 6150 }, { type: 'buy', quantity: 10, price: 6150 }, { type: 'sell', quantity: 12, price: 6950 }]
+         const incomingOrder = { type: 'sell', quantity: 25, price: 6150 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 6950 }, { type: 'sell', quantity: 5, price: 6150 }])
+       })
+
+       it.skip('Extra Credit: it fulfills a mismatched order when both parties benefit', () => {
+         const existingBook = [{ type: 'buy', quantity: 15, price: 6000 }, { type: 'sell', quantity: 12, price: 6950 }]
+         const incomingOrder = { type: 'sell', quantity: 15, price: 5900 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([{ type: 'sell', quantity: 12, price: 6950 }])
+       })
+
+       it.skip('Extra Credit: it does not fulfill a mismatched order when it does not benefit both parties', () => {
+         const existingBook = [{ type: 'buy', quantity: 15, price: 5900 }, { type: 'sell', quantity: 12, price: 6950 }]
+         const incomingOrder = { type: 'sell', quantity: 15, price: 6000 }
+
+         const updatedBook = reconcileOrder(existingBook, incomingOrder)
+
+         expect(updatedBook).to.deep.equal([
+           { type: 'buy', quantity: 15, price: 5900 },
+           { type: 'sell', quantity: 12, price: 6950 },
+           { type: 'sell', quantity: 15, price: 6000 },
+         ])
+       })
+     })
+   })
+
+   function typeFilter(exisitingBook, type) {
+    return existingBook.filter(item => item.type === type);
+  }
+  function reconcileOrder(existingBook, incomingOrder) {
+
+
+    let match = false;
+    let amount;
+    let i = 0;
+    for (; i < existingBook.length && !match; i++) {
+      if (existingBook[i].type != incomingOrder.type) {
+        if (existingBook[i].price === incomingOrder.price) {
+          match = true;
+          amount = (existingBook[i].quantity - incomingOrder.quantity);
+        }
+      }
+      if (match) {
+        break;
+      }
+    }
+
+    if (!match) {
+      existingBook.push(incomingOrder);
+    } else {
+      const matched = existingBook[i];
+      console.log(matched)
+      matched.quantity -= amount;
+      console.log(matched)
+
+      //remove the order from it's location
+      existingBook.splice(i, 1);
+
+      if (matched.quantity > 0) {
+        existingBook.push(matched);
+      }
+    }
+
+
+
+
+    return existingBook;
+  }
+
+  module.exports = reconcileOrder;
+

package.json

@@ -20,6 +20,6 @@
   "devDependencies": {
     "chai": "^4.2.0",
     "eslint": "^6.8.0",
-    "mocha": "^7.1.2"
+    "mocha": "^7.2.0"
   }
 }