Create dev-utils with blockchainLifecycle in it

packages/dev-utils/src/blockchain_lifecycle.ts

@@ -0,0 +1,26 @@
+import {RPC} from './rpc';
+
+export class BlockchainLifecycle {
+    private rpc: RPC;
+    private snapshotIdsStack: number[];
+    constructor(url: string) {
+        this.rpc = new RPC(url);
+        this.snapshotIdsStack = [];
+    }
+    // TODO: In order to run these tests on an actual node, we should check if we are running against
+    // TestRPC, if so, use snapshots, otherwise re-deploy contracts before every test
+    public async startAsync(): Promise<void> {
+        const snapshotId = await this.rpc.takeSnapshotAsync();
+        this.snapshotIdsStack.push(snapshotId);
+    }
+    public async revertAsync(): Promise<void> {
+        const snapshotId = this.snapshotIdsStack.pop() as number;
+        const didRevert = await this.rpc.revertSnapshotAsync(snapshotId);
+        if (!didRevert) {
+            throw new Error(`Snapshot with id #${snapshotId} failed to revert`);
+        }
+    }
+    public async mineABlock(): Promise<void> {
+        await this.rpc.mineBlockAsync();
+    }
+}

packages/dev-utils/src/index.ts

@@ -0,0 +1,2 @@
+export {RPC} from './rpc';
+export {BlockchainLifecycle} from './blockchain_lifecycle';

packages/dev-utils/src/rpc.ts

@@ -0,0 +1,61 @@
+import * as ethUtil from 'ethereumjs-util';
+import * as request from 'request-promise-native';
+
+export class RPC {
+    private url: string;
+    private port: number;
+    private id: number;
+    constructor(url: string) {
+        this.url = url;
+        this.id = 0;
+    }
+    public async takeSnapshotAsync(): Promise<number> {
+        const method = 'evm_snapshot';
+        const params: any[] = [];
+        const payload = this.toPayload(method, params);
+        const snapshotIdHex = await this.sendAsync(payload);
+        const snapshotId = ethUtil.bufferToInt(ethUtil.toBuffer(snapshotIdHex));
+        return snapshotId;
+    }
+    public async revertSnapshotAsync(snapshotId: number): Promise<boolean> {
+        const method = 'evm_revert';
+        const params = [snapshotId];
+        const payload = this.toPayload(method, params);
+        const didRevert = await this.sendAsync(payload);
+        return didRevert;
+    }
+    public async increaseTimeAsync(time: number) {
+        const method = 'evm_increaseTime';
+        const params = [time];
+        const payload = this.toPayload(method, params);
+        return this.sendAsync(payload);
+    }
+    public async mineBlockAsync(): Promise<void> {
+        const method = 'evm_mine';
+        const params: any[] = [];
+        const payload = this.toPayload(method, params);
+        await this.sendAsync(payload);
+    }
+    private toPayload(method: string, params: any[] = []): string {
+        const payload = JSON.stringify({
+            id: this.id,
+            method,
+            params,
+        });
+        this.id += 1;
+        return payload;
+    }
+    private async sendAsync(payload: string): Promise<any> {
+        const opts = {
+            method: 'POST',
+            uri: this.url,
+            body: payload,
+            headers: {
+                'content-type': 'application/json',
+            },
+        };
+        const bodyString = await request(opts);
+        const body = JSON.parse(bodyString);
+        return body.result;
+    }
+}