Merge pull request #3 from rolger/typescript_port

feature: first migration to typescript

TypeScript/.gitignore

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+node_modules/
+npm-debug.log
+typings
+.idea
+.iml
+src/*.js
+test/*.js
+*.js.map
+tsconfig.tsbuildinfo
+
+dist/
+coverage/
+.nyc_output/

TypeScript/README.md

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+# Dependency Breaking Katas
+
+Exercises to practice breaking dependencies in legacy
+code to create tests for it.
+
+## Goal
+
+We have some legacy code. We need to make changes.
+To make changes we need to introduce tests first.
+We might have to change some code to enable testing.
+We need to introduce so-called Seams (see [Michael
+Feathers' Working Effectively with Legacy
+Code](https://www.goodreads.com/book/show/44919.Working_Effectively_with_Legacy_Code)).
+
+Changing code without test is risky, so we want to
+
+* Only change as little code as possible.
+* Rely on automated Refactoring tools as much as possible.
+* You must not change the public API of the class.
+
+### Assignments for Techniques
+
+* Parametrise Constructor
+* Subclass And Override Method
+* Extract And Override Call
+* Replace Global Reference With Getter
+* Extract And Override Factory Method
+
+Planned
+
+* Extract Interface
+* Adapt Parameter
+
+### Task
+
+Each task presents you with a class and some collaborators.
+
+* Bring this class under test. Make sure to cover all paths in the core logic.
+* There is an existing test class with a first test case which might or might not work.
+* You cannot change collaborators because they are used by other teams as well.
+
+### License
+
+[New BSD License](http://opensource.org/licenses/bsd-license.php), see `license.txt` in repository.
+
+(This is a copied document - do not edit!)

TypeScript/TypeScript.iml

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+<?xml version="1.0" encoding="UTF-8"?>
+<module type="WEB_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>

TypeScript/app/a/Assignment.md

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+Assignment A
+============
+
+Goal
+----
+
+We have some legacy code. We need to make changes.
+To make changes we need to introduce tests first.
+We might have to change some code to enable testing.
+We need to introduce so-called Seams (see Michael
+Feathers' Working Effectively with Legacy Code).
+Changing code without test is risky, so we want to
+
+* Only change as little code as possible.
+* Rely on automated Refactoring tools as much as possible.
+* You must not change the public API of the class.
+
+Problem Category
+----------------
+
+The system under test depends on a collaborator with
+non deterministic behaviour. The collaborator is
+initialised in the constructor.
+
+Task
+----
+
+The given code calculates the discount for a purchase in
+our online shop. The main logic is in `Discount`.
+
+* Bring `Discount` under test. Make sure to cover all paths in the core logic.
+* There is an existing `DiscountTest` with a first test case which might or might not work.
+* You cannot change `MarketingCampaign` because it is used by other teams as well.

TypeScript/app/a/discount.ts

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+import {Money} from "./money";
+import {MarketingCampaign} from "./marketing-campaign";
+
+export class Discount {
+
+    marketingCampaign: MarketingCampaign;
+
+    constructor() {
+        this.marketingCampaign = new MarketingCampaign();
+    }
+
+    discountFor(netPrice: Money): Money {
+        if (this.marketingCampaign.isCrazySalesDay()) {
+            return netPrice.reduceBy(15);
+        }
+        if (netPrice.moreThan(Money.ONE_THOUSAND)) {
+            return netPrice.reduceBy(10);
+        }
+        if (netPrice.moreThan(Money.ONE_HUNDRED) && this.marketingCampaign.isActive()) {
+            return netPrice.reduceBy(5);
+        }
+        return netPrice;
+    }
+}

TypeScript/app/a/marketing-campaign.ts

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+export class MarketingCampaign {
+
+    public isActive(): boolean {
+        let now: Date = new Date();
+        return now.getMilliseconds() % 2 == 0;
+    }
+
+    public isCrazySalesDay(): boolean {
+        let now: Date = new Date();
+        return now.getDay() === 5;
+    }
+
+}

TypeScript/app/a/money.ts

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+export class Money {
+
+    public static readonly ONE_THOUSAND: Money = new Money(1000);
+    public static readonly ONE_HUNDRED: Money = new Money(100);
+
+    value: number;
+
+    constructor(value: number | string) {
+        if (typeof value === 'string') {
+            this.value = Number.parseFloat(value);
+        } else {
+            this.value = value;
+        }
+    }
+
+    reduceBy(p: number): Money {
+        // value.multiply(new BigDecimal(100 - p)).divide(new BigDecimal(100))
+        return new Money((this.value * (100 - p) / 100).toFixed(2));
+    }
+
+    moreThan(other: Money): boolean {
+        return this.value > other.value;
+    }
+
+}

TypeScript/app/b/Assignment.md

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+Assignment B
+============
+
+Goal
+----
+
+We have some legacy code. We need to make changes.
+To make changes we need to introduce tests first.
+We might have to change some code to enable testing.
+We need to introduce so-called Seams (see Michael
+Feathers' Working Effectively with Legacy Code).
+Changing code without test is risky, so we want to
+
+* Only change as little code as possible.
+* Rely on automated Refactoring tools as much as possible.
+* You must not change the public API of the class.
+
+Problem Category
+----------------
+
+The system under test contains non deterministic behaviour,
+which is located in a few methods. The system under test can
+be sub-classed.
+
+Task
+----
+
+The given `MarketingCampaign` controls the marketing actions which
+run on our online shop. During campaigns we e.g. offer discounts.
+
+* Bring `MarketingCampaign` under test. Make sure to cover all paths in the core logic.
+* There is an existing `MarketingCampaignTest` with a first test case which might or might not work.

TypeScript/app/b/marketing-campaign.ts

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+export class MarketingCampaign {
+
+    public isActive(): boolean {
+        return this.milliseconds() % 2 == 0;
+    }
+
+    public isCrazySalesDay(): boolean {
+        return this.dayOfWeek() == 5;
+    }
+
+    private milliseconds(): number {
+        let now: Date = new Date();
+        return now.getMilliseconds();
+    }
+
+    private dayOfWeek(): number {
+        let date: Date = new Date();
+        return date.getDay();
+    }
+}

TypeScript/app/c/Assignment.md

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+Assignment C
+============
+
+Goal
+----
+
+We have some legacy code. We need to make changes.
+To make changes we need to introduce tests first.
+We might have to change some code to enable testing.
+We need to introduce so-called Seams (see Michael
+Feathers' Working Effectively with Legacy Code).
+Changing code without test is risky, so we want to
+
+* Only change as little code as possible.
+* Rely on automated Refactoring tools as much as possible.
+* You must not change the public API of the class.
+
+Problem Category
+----------------
+
+The system under test depends on a collaborator with
+database access. The database is not available in our
+test environment. The collaborator is a static call.
+
+Task
+----
+
+The given code creates the receipt with the calculated tax
+for a purchase in our online shop. The main logic is in `Checkout`.
+
+* Bring `Checkout` under test. Make sure to cover all paths in the core logic.
+* There is an existing `CheckoutTest` with a first test case which might or might not work.
+* You cannot change `ReceiptRepository` because it is used by other teams as well.

TypeScript/app/c/checkout.ts

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+import {Money} from "./money";
+import {Receipt} from "./receipt";
+import {ReceiptRepository} from "./receipt-repository";
+
+
+export class Checkout {
+
+    createReceipt(netAmount: Money): Promise<Error | boolean> {
+        let tax = netAmount.percentage(20);
+        let total = netAmount.add(tax);
+        let receipt: Receipt = new Receipt(netAmount, tax, total);
+
+        return ReceiptRepository.store(receipt);
+    }
+}

TypeScript/app/c/money.ts

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+export class Money {
+
+    public static readonly ZERO: Money = new Money(0);
+    public static readonly ONE_THOUSAND: Money = new Money(1000);
+    public static readonly ONE_HUNDRED: Money = new Money(100);
+
+    value: number;
+
+    constructor(value: number | string) {
+        if (typeof value === 'string') {
+            this.value = Number.parseFloat(value);
+        } else {
+            this.value = value;
+        }
+    }
+
+     add(other: Money): Money {
+        return new Money(this.value + other.value);
+    }
+
+     percentage(p: number): Money {
+        return new Money((this.value * p / 100).toFixed(2));
+    }
+
+     moreThan(other: Money): boolean {
+        return this.value > other.value;
+    }
+
+     format(): string {
+        return this.value.toFixed(2);
+    }
+
+
+}

TypeScript/app/c/receipt-repository.ts

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+import {Receipt} from "./receipt";
+import {Connection, MysqlError} from "mysql";
+
+let mysql = require('mysql');
+
+const db: Connection = mysql.createConnection({
+    host: 'localhost:3306',
+    user: 'store',
+    password: '12345',
+    database: 'store'
+});
+
+export class ReceiptRepository {
+
+    static store(receipt: Receipt): Promise<Error | boolean> {
+        return new Promise((resolve, reject) => {
+            db.connect((err: MysqlError) => {
+                if (err) {
+                    reject(err);
+                } else {
+
+                    db.query(
+                        "insert into RECEIPT (AMOUNT, TAX, TOTAL) values(?, ?, ?)",
+                        [receipt.amount.value, receipt.tax.value, receipt.total.value],
+                        (err, results) => {
+                            if (err) {
+                                reject(err);
+                            }
+                            if (!results[0]) {
+                                reject(new Error('Data not inserted?'))
+                            }
+                            resolve(true);
+                        });
+
+                    db.end();
+                }
+            });
+        });
+    }
+}

TypeScript/app/c/receipt.ts

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+import {Money} from "./money";
+
+export class Receipt {
+    constructor(public amount: Money, public tax: Money, public total:Money) {
+        this.amount = Money.ZERO;
+        this.tax = Money.ZERO;
+    }
+}

TypeScript/app/d/Assignment.md

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+Assignment D
+============
+
+Goal
+----
+
+We have some legacy code. We need to make changes.
+To make changes we need to introduce tests first.
+We might have to change some code to enable testing.
+We need to introduce so-called Seams (see Michael
+Feathers' Working Effectively with Legacy Code).
+Changing code without test is risky, so we want to
+
+* Only change as little code as possible.
+* Rely on automated Refactoring tools as much as possible.
+* You must not change the public API of the class.
+
+Problem Category
+----------------
+
+The system under test depends on a collaborator with
+slow behaviour due to a HTTP call. It is not guaranteed
+that the REST server is available. The collaborator is
+a Singleton and called multiple times.
+
+Task
+----
+
+The given code calculates the shipping cost for a purchase
+depending on the destination in our online shop. The main
+logic is in `ShippingCost`.
+
+* Bring `ShippingCost` under test. Make sure to cover all paths in the core logic.
+* There is an existing `ShippingCostTest` with a first test case which might or might not work.
+* You cannot change `RestCountriesAPI` because it is used by other teams as well.