feat(infra): Expose abstract Shard class [CLK-187171] (#3)

Author: Justinon

API.md

@@ -1,4 +1,4 @@
-export interface IShard {
+export interface IShardProps {
   /**
    * The cidr for a shard's vpc.
    * Regions typically receive a 10.?.0.0/12 address space,
@@ -10,13 +10,32 @@ export interface IShard {
    */
   readonly region: string;
   /**
-   * The proper name for a shard (without numeric suffix).
+   * The shard-number within the region.
    */
-  readonly name: string;
+  readonly number: number;
+}
+
+export interface IShard extends IShardProps {
   /**
-   * The shard-number within the region.
+   * The proper name for a shard (without numeric suffix).
    */
+  readonly name: string;
+}
+
+export abstract class Shard implements IShard {
+  readonly cidr: string;
+  readonly region: string;
   readonly number: number;
 
-  toString(): string;
+  constructor(props: IShardProps) {
+    this.cidr = props.cidr;
+    this.region = props.region;
+    this.number = props.number;
+  }
+
+  /**
+   * There are numerous different ways to name a shard. Pick one and stick with
+   * it.
+   */
+  abstract get name(): string;
 }

src/Shard.ts

@@ -0,0 +1,30 @@
+import { IShard, Shard, IShardProps } from '../src';
+
+const env = 'QA';
+class TestShardImpl extends Shard {
+  get name(): string {
+    return `${env}_${this.region}_${this.number}`;
+  }
+}
+
+const testShardProps: IShardProps = { cidr: '10.0.0.0/0', region: 'us-west-2', number: 1 };
+
+let shard: IShard;
+describe('Shard', () => {
+  beforeEach(() => {
+    shard = new TestShardImpl(testShardProps);
+  });
+
+  it('sets CIDR correctly', () => {
+    expect(shard.cidr).toEqual(testShardProps.cidr);
+  });
+  it('sets region correctly', () => {
+    expect(shard.region).toEqual(testShardProps.region);
+  });
+  it('sets number correctly', () => {
+    expect(shard.number).toEqual(testShardProps.number);
+  });
+  it('sets name correctly', () => {
+    expect(shard.name).toEqual('QA_us-west-2_1');
+  });
+});