Remove non-null assertions and refactor errors

src/commands.ts

@@ -7,6 +7,7 @@ import * as fs from 'fs';
 import * as opn from 'opn';
 import * as path from 'path';
 import * as vscode from 'vscode';
+import * as errors from './errors';
 import * as FunctionsCli from './functions-cli';
 import { FunctionAppNode, INode } from './nodes';
 import * as TemplateFiles from './template-files';
@@ -28,7 +29,7 @@ export async function createFunction(outputChannel: vscode.OutputChannel): Promi
     let functionAppPath: string;
     const folders: vscode.WorkspaceFolder[] | undefined = vscode.workspace.workspaceFolders;
     if (!folders || folders.length === 0) {
-        throw new util.NoWorkspaceError();
+        throw new errors.NoWorkspaceError();
     } else if (folders.length === 1) {
         functionAppPath = folders[0].uri.fsPath;
     } else {
@@ -44,7 +45,7 @@ export async function createFunction(outputChannel: vscode.OutputChannel): Promi
         if (result === yes) {
             await FunctionsCli.createFunctionApp(outputChannel, functionAppPath);
         } else {
-            throw new util.UserCancelledError();
+            throw new errors.UserCancelledError();
         }
     }
 

src/errors.ts

@@ -0,0 +1,16 @@
+/*---------------------------------------------------------------------------------------------
+ *  Copyright (c) Microsoft Corporation. All rights reserved.
+ *  Licensed under the MIT License. See License.txt in the project root for license information.
+ *--------------------------------------------------------------------------------------------*/
+
+export class UserCancelledError extends Error { }
+
+export class NoWorkspaceError extends Error {
+    public message: string = 'You must have a workspace open to perform this operation.';
+}
+
+export class ArgumentError extends Error {
+    constructor(obj: object) {
+        super(`Invalid ${obj.constructor.name}.`);
+    }
+}

src/extension.ts

@@ -8,6 +8,7 @@
 import * as vscode from 'vscode';
 import { AzureAccount } from './azure-account.api';
 import * as commands from './commands';
+import * as errors from './errors';
 import { AzureFunctionsExplorer } from './explorer';
 import { FunctionAppNode, INode } from './nodes';
 import { Reporter } from './telemetry';
@@ -16,8 +17,12 @@ import * as util from './util';
 export function activate(context: vscode.ExtensionContext): void {
     context.subscriptions.push(new Reporter(context));
 
-    const azureAccount: AzureAccount = vscode.extensions.getExtension<AzureAccount>('ms-vscode.azure-account')!.exports;
-    if (azureAccount) {
+    const azureAccountExtension: vscode.Extension<AzureAccount> | undefined = vscode.extensions.getExtension<AzureAccount>('ms-vscode.azure-account');
+    if (!azureAccountExtension || !azureAccountExtension.exports) {
+        vscode.window.showErrorMessage('The Azure Account Extension is required for the Azure Functions extension.');
+    } else {
+        const azureAccount: AzureAccount = azureAccountExtension.exports;
+
         context.subscriptions.push(azureAccount.onFiltersChanged(() => explorer.refresh()));
         context.subscriptions.push(azureAccount.onStatusChanged(() => explorer.refresh()));
 
@@ -34,8 +39,6 @@ export function activate(context: vscode.ExtensionContext): void {
         initAsyncCommand(context, 'azureFunctions.startFunctionApp', (node?: FunctionAppNode) => commands.startFunctionApp(outputChannel, node));
         initAsyncCommand(context, 'azureFunctions.stopFunctionApp', (node?: FunctionAppNode) => commands.stopFunctionApp(outputChannel, node));
         initAsyncCommand(context, 'azureFunctions.restartFunctionApp', (node?: FunctionAppNode) => commands.restartFunctionApp(outputChannel, node));
-    } else {
-        vscode.window.showErrorMessage('The Azure Account Extension is required for the Azure Functions extension.');
     }
 }
 
@@ -56,7 +59,7 @@ function initAsyncCommand(context: vscode.ExtensionContext, commandId: string, c
         try {
             args.length === 0 ? await callback() : await callback(<INode>args[0]);
         } catch (error) {
-            if (error instanceof util.UserCancelledError) {
+            if (error instanceof errors.UserCancelledError) {
                 result = 'Canceled';
                 // Swallow the error so that it's not displayed to the user
             } else {

src/nodes.ts

@@ -7,6 +7,7 @@ import * as path from 'path';
 import * as vscode from 'vscode';
 import { Site, WebAppCollection } from '../node_modules/azure-arm-website/lib/models';
 import { AzureResourceFilter } from './azure-account.api';
+import * as errors from './errors';
 import * as util from './util';
 
 export interface INode extends vscode.TreeItem {
@@ -44,9 +45,13 @@ export class SubscriptionNode implements INode {
     private readonly subscriptionFilter: AzureResourceFilter;
 
     constructor(subscriptionFilter: AzureResourceFilter) {
+        if (!subscriptionFilter.subscription.displayName || !subscriptionFilter.subscription.subscriptionId) {
+            throw new errors.ArgumentError(subscriptionFilter);
+        }
+
         this.subscriptionFilter = subscriptionFilter;
-        this.label = subscriptionFilter.subscription.displayName!;
-        this.id = subscriptionFilter.subscription.subscriptionId!;
+        this.label = subscriptionFilter.subscription.displayName;
+        this.id = subscriptionFilter.subscription.subscriptionId;
         this.tenantId = subscriptionFilter.session.tenantId;
     }
 
@@ -61,8 +66,8 @@ export class SubscriptionNode implements INode {
         const webApps: WebAppCollection = await this.getWebSiteClient().webApps.list();
 
         return webApps.filter((s: Site) => s.kind === 'functionapp')
-            .sort((s1: Site, s2: Site) => s1.id!.localeCompare(s2.id!))
-            .map((s: Site) => new FunctionAppNode(s, this));
+            .map((s: Site) => new FunctionAppNode(s, this))
+            .sort((f1: FunctionAppNode, f2: FunctionAppNode) => f1.id.localeCompare(f2.id));
     }
 
     public getWebSiteClient(): WebSiteManagementClient {
@@ -76,14 +81,20 @@ export class FunctionAppNode implements INode {
     public readonly id: string;
     public readonly tenantId: string;
 
-    private readonly functionApp: Site;
+    private readonly resourceGroup: string;
+    private readonly name: string;
     private readonly subscriptionNode: SubscriptionNode;
 
     constructor(functionApp: Site, subscriptionNode: SubscriptionNode) {
-        this.functionApp = functionApp;
+        if (!functionApp.id || !functionApp.resourceGroup || !functionApp.name) {
+            throw new errors.ArgumentError(functionApp);
+        }
+
+        this.id = functionApp.id;
+        this.resourceGroup = functionApp.resourceGroup;
+        this.name = functionApp.name;
         this.subscriptionNode = subscriptionNode;
-        this.label = `${functionApp.name} (${this.functionApp.resourceGroup})`;
-        this.id = functionApp.id!;
+        this.label = `${functionApp.name} (${this.resourceGroup})`;
         this.tenantId = subscriptionNode.tenantId;
     }
 
@@ -96,14 +107,14 @@ export class FunctionAppNode implements INode {
 
     public async start(): Promise<void> {
         const client: WebSiteManagementClient = this.subscriptionNode.getWebSiteClient();
-        await client.webApps.start(this.functionApp.resourceGroup!, this.functionApp.name!);
-        await util.waitForFunctionAppState(client, this.functionApp.resourceGroup!, this.functionApp.name!, util.FunctionAppState.Running);
+        await client.webApps.start(this.resourceGroup, this.name);
+        await util.waitForFunctionAppState(client, this.resourceGroup, this.name, util.FunctionAppState.Running);
     }
 
     public async stop(): Promise<void> {
         const client: WebSiteManagementClient = this.subscriptionNode.getWebSiteClient();
-        await client.webApps.stop(this.functionApp.resourceGroup!, this.functionApp.name!);
-        await util.waitForFunctionAppState(client, this.functionApp.resourceGroup!, this.functionApp.name!, util.FunctionAppState.Stopped);
+        await client.webApps.stop(this.resourceGroup, this.name);
+        await util.waitForFunctionAppState(client, this.resourceGroup, this.name, util.FunctionAppState.Stopped);
     }
 
     public async restart(): Promise<void> {

src/util.ts

@@ -7,6 +7,7 @@ import WebSiteManagementClient = require('azure-arm-website');
 import * as fs from 'fs';
 import * as vscode from 'vscode';
 import { Site } from '../node_modules/azure-arm-website/lib/models';
+import * as errors from './errors';
 import { reporter } from './telemetry';
 
 export function sendTelemetry(eventName: string, properties?: { [key: string]: string; }, measures?: { [key: string]: number; }): void {
@@ -42,7 +43,7 @@ export async function showQuickPick(items: vscode.QuickPickItem[] | Thenable<vsc
     const result: vscode.QuickPickItem | undefined = await vscode.window.showQuickPick(items, options);
 
     if (!result) {
-        throw new UserCancelledError();
+        throw new errors.UserCancelledError();
     } else {
         return result;
     }
@@ -58,7 +59,7 @@ export async function showInputBox(placeHolder: string, prompt: string, ignoreFo
     const result: string | undefined = await vscode.window.showInputBox(options);
 
     if (!result) {
-        throw new UserCancelledError();
+        throw new errors.UserCancelledError();
     } else {
         return result;
     }
@@ -76,7 +77,7 @@ export async function showFolderDialog(): Promise<string> {
     const result: vscode.Uri[] | undefined = await vscode.window.showOpenDialog(options);
 
     if (!result || result.length === 0) {
-        throw new UserCancelledError();
+        throw new errors.UserCancelledError();
     } else {
         return result[0].fsPath;
     }
@@ -124,9 +125,3 @@ export function writeToFile(path: string, data: string): Promise<void> {
         });
     });
 }
-
-export class UserCancelledError extends Error { }
-
-export class NoWorkspaceError extends Error {
-    public message: string = 'You must have a workspace open to perform this operation.';
-}