Add unit test for test discovery

When directory is not present.

extensions/ql-vscode/src/databases-ui.ts

@@ -384,7 +384,7 @@ export class DatabaseUI extends DisposableObject {
       !(await fs.pathExists(this.storagePath) ||
         !(await fs.stat(this.storagePath)).isDirectory())
     ) {
-      // ignore a missing or invalid storage directory.
+      logger.log('Missing or invalid storage directory. Not trying to remove orphaned databases.');
       return;
     }
 

extensions/ql-vscode/src/vscode-tests/minimal-workspace/qltest-discovery.test.ts

@@ -2,12 +2,15 @@ import 'vscode-test';
 import 'mocha';
 import { Uri, WorkspaceFolder } from 'vscode';
 import { expect } from 'chai';
+import * as fs from 'fs-extra';
+import * as sinon from 'sinon';
 
 import { QLTestDiscovery } from '../../qltest-discovery';
 
 describe('qltest-discovery', () => {
   describe('discoverTests', () => {
-    it('should run discovery', async () => {
+    let sandbox: sinon.SinonSandbox;
+
     const baseUri = Uri.parse('file:/a/b');
     const baseDir = baseUri.fsPath;
     const cDir = Uri.parse('file:/a/b/c').fsPath;
@@ -15,7 +18,11 @@ describe('qltest-discovery', () => {
     const eFile = Uri.parse('file:/a/b/c/e.ql').fsPath;
     const hDir = Uri.parse('file:/a/b/c/f/g/h').fsPath;
     const iFile = Uri.parse('file:/a/b/c/f/g/h/i.ql').fsPath;
-      const qlTestDiscover = new QLTestDiscovery(
+    let qlTestDiscover: QLTestDiscovery;
+
+    beforeEach(() => {
+      sandbox = sinon.createSandbox();
+      qlTestDiscover = new QLTestDiscovery(
         {
           uri: baseUri,
           name: 'My tests'
@@ -31,6 +38,15 @@ describe('qltest-discovery', () => {
         } as any
       );
 
+    });
+
+    afterEach(() => {
+      sandbox.restore();
+    });
+
+    it('should run discovery', async () => {
+      sandbox.stub(fs, 'pathExists').resolves(true);
+
       const result = await (qlTestDiscover as any).discover();
       expect(result.watchPath).to.eq(baseDir);
       expect(result.testDirectory.path).to.eq(baseDir);
@@ -56,5 +72,15 @@ describe('qltest-discovery', () => {
       expect(children[0].path).to.eq(iFile);
       expect(children[0].name).to.eq('i.ql');
     });
+
+    it('should avoid discovery if a folder does not exist', async () => {
+      sandbox.stub(fs, 'pathExists').resolves(false);
+      const result = await (qlTestDiscover as any).discover();
+      expect(result.watchPath).to.eq(baseDir);
+      expect(result.testDirectory.path).to.eq(baseDir);
+      expect(result.testDirectory.name).to.eq('My tests');
+
+      expect(result.testDirectory.children.length).to.eq(0);
+    });
   });
 });