diff --git a/dev-packages/cli/src/run-test.ts b/dev-packages/cli/src/run-test.ts
index b3284dd19b9ef..76a004c08e5cc 100644
--- a/dev-packages/cli/src/run-test.ts
+++ b/dev-packages/cli/src/run-test.ts
@@ -36,15 +36,25 @@ export default async function runTest(options: TestOptions): Promise<void> {
         matchAppUrl: () => true, // all urls are application urls
         newPage: async () => {
             const browser = await puppeteer.launch(launch);
-            return browser.newPage();
+            // re-use empty tab
+            const [tab] = await browser.pages();
+            return tab;
         },
         onWillRun: async () => {
+            const promises = [];
             if (options.coverage) {
-                await Promise.all([
-                    testPage.coverage.startJSCoverage(),
-                    testPage.coverage.startCSSCoverage()
-                ]);
+                promises.push(testPage.coverage.startJSCoverage());
+                promises.push(testPage.coverage.startCSSCoverage());
+            }
+            // When launching in non-headless mode (with a UI and dev-tools open), make sure
+            // the app has focus, to avoid failures of tests that query the UI's state.
+            if (launch && launch.devtools) {
+                promises.push(testPage.waitForSelector('#theia-app-shell.p-Widget.theia-ApplicationShell')
+                    .then(e => e.click()));
             }
+            // Clear application's local storage to avoid reusing previous state
+            promises.push(testPage.evaluate(() => localStorage.clear()));
+            await Promise.all(promises);
         },
         onDidRun: async failures => {
             if (options.coverage) {
@@ -56,6 +66,8 @@ export default async function runTest(options: TestOptions): Promise<void> {
                 require('puppeteer-to-istanbul').write([...jsCoverage, ...cssCoverage]);
             }
             if (exit) {
+                // allow a bit of time to finish printing-out test results
+                await new Promise(resolve => setTimeout(resolve, 1000));
                 await testPage.close();
                 process.exit(failures > 0 ? 1 : 0);
             }
diff --git a/dev-packages/cli/src/test-page.ts b/dev-packages/cli/src/test-page.ts
index 29e50554f2a10..f94ddedb618da 100644
--- a/dev-packages/cli/src/test-page.ts
+++ b/dev-packages/cli/src/test-page.ts
@@ -113,7 +113,7 @@ export default async function newTestPage(options: TestPageOptions): Promise<pup
                 reporter: 'spec',
                 ui: 'bdd',
                 color: true,
-                retries: 5
+                retries: 0
             });
         });
 
diff --git a/dev-packages/cli/src/theia.ts b/dev-packages/cli/src/theia.ts
index 3a5df9dc57848..0a7e38b80cf55 100644
--- a/dev-packages/cli/src/theia.ts
+++ b/dev-packages/cli/src/theia.ts
@@ -525,6 +525,8 @@ async function theiaCli(): Promise<void> {
                     }),
                     launch: {
                         args: ['--no-sandbox'],
+                        // eslint-disable-next-line no-null/no-null
+                        defaultViewport: null, // view port can take available space instead of 800x600 default
                         devtools: testInspect
                     },
                     files: {