Added first test

Author: ecmel

package-lock.json

@@ -73,4 +73,4 @@
 		"webpack": "^5.9.0",
 		"webpack-cli": "^4.2.0"
 	}
-}
+}

package.json

@@ -1,15 +1,91 @@
 import * as assert from 'assert';
+import { ClassCompletionItemProvider } from '../../extension';
+import {
+	window,
+	TextDocument,
+	Position,
+	CancellationToken,
+	Event,
+	CompletionContext,
+	CompletionTriggerKind,
+	EndOfLine,
+	Range,
+	TextLine,
+	Uri,
+	CompletionItem
+} from 'vscode';
 
-// You can import and use all API from the 'vscode' module
-// as well as import your extension to test it
-import * as vscode from 'vscode';
-// import * as myExtension from '../../extension';
+class MockCancellationToken implements CancellationToken {
+	isCancellationRequested: boolean;
+	onCancellationRequested!: Event<any>;
+
+	constructor(isCancellationRequested: boolean) {
+		this.isCancellationRequested = isCancellationRequested;
+	}
+}
+
+class MockCompletionContext implements CompletionContext {
+	triggerKind = CompletionTriggerKind.Invoke;
+	triggerCharacter?: string | undefined;
+}
+
+class MockTextDocument implements TextDocument {
+	uri!: Uri;
+	fileName!: string;
+	isUntitled!: boolean;
+	languageId!: string;
+	version!: number;
+	isDirty!: boolean;
+	isClosed!: boolean;
+	eol!: EndOfLine;
+	lineCount!: number;
+	readonly #text: string;
+
+	constructor(text: string) {
+		this.#text = text;
+	}
+
+	getText(range?: Range): string {
+		return this.#text;
+	}
+	save(): Thenable<boolean> {
+		throw new Error('Method not implemented.');
+	}
+	lineAt(position: Position | number | any): TextLine | any {
+		throw new Error('Method not implemented.');
+	}
+	offsetAt(position: Position): number {
+		throw new Error('Method not implemented.');
+	}
+	positionAt(offset: number): Position {
+		throw new Error('Method not implemented.');
+	}
+	getWordRangeAtPosition(position: Position, regex?: RegExp): Range | undefined {
+		throw new Error('Method not implemented.');
+	}
+	validateRange(range: Range): Range {
+		throw new Error('Method not implemented.');
+	}
+	validatePosition(position: Position): Position {
+		throw new Error('Method not implemented.');
+	}
+}
 
 suite('Extension Test Suite', () => {
-	vscode.window.showInformationMessage('Start all tests.');
+	window.showInformationMessage('Start all tests.');
+
+	test('Completes empty document with no items.', done => {
+		const provider = new ClassCompletionItemProvider();
+
+		const document = new MockTextDocument("");
+		const position = new Position(0, 0);
+		const token = new MockCancellationToken(false);
+		const context = new MockCompletionContext();
+
+		const result = provider.provideCompletionItems(document, position, token, context) as Thenable<CompletionItem[]>;
 
-	test('Sample test', () => {
-		assert.strictEqual(-1, [1, 2, 3].indexOf(5));
-		assert.strictEqual(-1, [1, 2, 3].indexOf(0));
+		result.then((items) => {
+			assert.strictEqual(items.length, 0);
+		}, done);
 	});
 });