diff --git a/test/README.md b/test/README.md
index ed3796006..5569f23c2 100644
--- a/test/README.md
+++ b/test/README.md
@@ -2,39 +2,21 @@
 
 ## Executing tests
 
-We start a new VS Code instance for each `fixture` directory in `fixtures/*/`, which includes a TeX file for tests, and execute an appropriate test defined in `*.test.ts` while skipping other tests not related to the directory. For tests of building a LaTeX file, we try to build a LaTeX file in the directory. If a PDF file is not generated, the test fails. With this approach, we can debug the extension by opening a TeX file in the `fixture` directory if the test fails.
-
-### How tests executed
-
-1. `runTest.ts` starts a new VS Code instance for each `fixture` directory and executes `*.index.ts`.
-2. `*.index.ts` runs all the tests defined in `*.test.ts`.
-3. Tests in `*.test.ts` are executed through `runTestWithFixture`.
-4. `runTestWithFixture` skip tests in `*.test.ts` if they are not related to the current `fixture` directory.
-
-### Unit tests
-
-Unit tests are under the `unittests` directory.
-
----
-
-## New Tests
-
-We start a new VS Code instance for each `fixture` directory in `fixtures/*/`, which includes a series of TeX-related files for tests, and execute appropriate tests defined in `suites/*.test.ts` while skipping other tests not related to the directory.
+We start a new VS Code instance for `testground`, `multiroot`, and `viewer` directories in `test/fixtures/`, which includes a series of TeX-related files for tests, and execute appropriate tests defined in `suites/*.test.ts` (`viewer.test.ts` for `viewer` fixture) while skipping other tests not related to the directory.
 For tests of building a LaTeX file, we try to build a LaTeX file in the directory.
 If a PDF file is not generated, the test fails.
-With this approach, we can debug the extension by opening a TeX file in the `fixture` directory if the test fails.
+The TeX files related are automatically created before the test and removed after.
 
 ### How tests are executed via CLI
 
-1. `runTest.ts` starts a new VS Code instance for each `fixture` directory and executes `suites/index.ts`.
-2. `index.ts` runs all the tests defined in `*.test.ts`.
-3. Tests in `*.test.ts` are executed through `runTest` defined in `suites/utils.ts`, which skip tests in `*.test.ts` if they are not related to the current `fixture` directory.
+1. `runTest.ts` starts a new VS Code instance for each `fixture` directory and executes `suites/index.ts` (`viewer.test.ts` for `viewer` fixture).
+2. Tests in `*.test.ts` are executed through `runTest` defined in `suites/utils.ts`, which skip tests in `*.test.ts` if they are not related to the current `fixture` directory.
 
 ### How tests are executed via VS Code launch
 
 We have a `Run Tests` launch configuration in `.vscode/launch.json`.
-In the config item, the first `args` passed to `code` defines the workspace to open, which is just the `fixture` directory to execute.
-Additionally, the `LATEXWORKSHOP_CISUITE` envvar defines the suites to be executed, separated by commas and all if left empty.
+In the config item, the first `args` passed to `code` defines the workspace to open: `testground` typically, and `multiroot/resource.code-workspace` for the multi-root workspace tests.
+Additionally, the `LATEXWORKSHOP_SUITE` envvar defines the suites to be executed, separated by commas and all if left empty.
 
 
 ## Executing Tests on GitHub Actions
diff --git a/test/suites/01_build.test.ts b/test/suites/01_build.test.ts
index 9bec3ad56..ae6267757 100644
--- a/test/suites/01_build.test.ts
+++ b/test/suites/01_build.test.ts
@@ -1,23 +1,20 @@
 import * as vscode from 'vscode'
 import * as path from 'path'
 import rimraf from 'rimraf'
-import * as assert from 'assert'
 
-import { Extension, activate } from '../../src/main'
-import { assertBuild, runTest, waitBuild, writeTeX } from './utils'
+import { Extension } from '../../src/main'
+import { assertBuild, getExtension, runTest, waitBuild, writeTeX } from './utils'
 import { sleep } from '../utils/ciutils'
 
 suite('Build TeX files test suite', () => {
 
-    let extension: Extension | undefined
+    let extension: Extension
     const suiteName = path.basename(__filename).replace('.test.js', '')
     let fixture = path.resolve(__dirname, '../../../test/fixtures/testground')
     const fixtureName = 'testground'
 
     suiteSetup(async () => {
-        await vscode.commands.executeCommand('latex-workshop.activate')
-        extension = vscode.extensions.getExtension<ReturnType<typeof activate>>('James-Yu.latex-workshop')?.exports.extension
-        assert.ok(extension)
+        extension = await getExtension()
         fixture = path.resolve(extension.extensionRoot, 'test/fixtures/testground')
     })
 
@@ -28,7 +25,6 @@ suite('Build TeX files test suite', () => {
     teardown(async () => {
         await vscode.commands.executeCommand('workbench.action.closeAllEditors')
         if (extension) {
-            extension.manager.invalidateCache()
             extension.manager.rootFile = undefined
         }
 
@@ -42,8 +38,7 @@ suite('Build TeX files test suite', () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.exclude', undefined)
 
         if (path.basename(fixture) === 'testground') {
-            await sleep(250)
-            rimraf(fixture + '/*', (e) => {if (e) {console.error(e)}})
+            rimraf(fixture + '/{*,.vscode}', (e) => {if (e) {console.error(e)}})
             await sleep(500) // Required for pooling
         }
     })
@@ -67,14 +62,14 @@ suite('Build TeX files test suite', () => {
         await assertBuild({fixture, texFileName: 'main.tex', pdfFileName: 'main.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root 1'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root and build 1'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', true)
         await writeTeX('subfile', fixture)
         await assertBuild({fixture, texFileName: 'sub/s.tex', pdfFileName: 'sub/s.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root 2'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root and build 2'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', false)
         await writeTeX('subfile', fixture)
@@ -87,20 +82,6 @@ suite('Build TeX files test suite', () => {
         await assertBuild({fixture, texFileName: 'main.tex', pdfFileName: 'out/main.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'detect root with search.rootFiles.include'}, async () => {
-        await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
-        await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.include', ['alt/*.tex'])
-        await writeTeX('subfiletwomain', fixture)
-        await assertBuild({fixture, texFileName: 'sub/s.tex', pdfFileName: 'alt/main.pdf', extension})
-    })
-
-    runTest({suiteName, fixtureName, testName: 'detect root with search.rootFiles.exclude'}, async () => {
-        await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
-        await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.exclude', ['*.tex'])
-        await writeTeX('subfiletwomain', fixture)
-        await assertBuild({fixture, texFileName: 'sub/s.tex', pdfFileName: 'alt/main.pdf', extension})
-    })
-
     runTest({suiteName, fixtureName, testName: 'basic build with spaces in names'}, async () => {
         await writeTeX('main', fixture, {fileName: 'main space/main.tex'})
         await assertBuild({fixture, texFileName: 'main space/main.tex', pdfFileName: 'main space/main.pdf', extension})
@@ -112,11 +93,6 @@ suite('Build TeX files test suite', () => {
         await assertBuild({fixture, texFileName: 'main.tex', pdfFileName: 'out space/main.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect root with verbatim'}, async () => {
-        await writeTeX('subfileverbatim', fixture)
-        await assertBuild({fixture, texFileName: 'sub/s.tex', pdfFileName: 'main.pdf', extension})
-    })
-
     runTest({suiteName, fixtureName, testName: 'build with magic comment'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.recipes', [])
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.build.forceRecipeUsage', false)
diff --git a/test/suites/02_autobuild.test.ts b/test/suites/02_autobuild.test.ts
index 3d77d9c18..c0a6b8a3b 100644
--- a/test/suites/02_autobuild.test.ts
+++ b/test/suites/02_autobuild.test.ts
@@ -1,23 +1,20 @@
 import * as vscode from 'vscode'
 import * as path from 'path'
-import * as assert from 'assert'
 import rimraf from 'rimraf'
 
-import { Extension, activate } from '../../src/main'
-import { assertAutoBuild, assertBuild, runTest, writeTeX } from './utils'
+import { Extension } from '../../src/main'
+import { assertAutoBuild, assertBuild, getExtension, runTest, writeTeX } from './utils'
 import { sleep } from '../utils/ciutils'
 
 suite('Auto-build test suite', () => {
 
-    let extension: Extension | undefined
+    let extension: Extension
     const suiteName = path.basename(__filename).replace('.test.js', '')
     let fixture = path.resolve(__dirname, '../../../test/fixtures/testground')
     const fixtureName = 'testground'
 
     suiteSetup(async () => {
-        await vscode.commands.executeCommand('latex-workshop.activate')
-        extension = vscode.extensions.getExtension<ReturnType<typeof activate>>('James-Yu.latex-workshop')?.exports.extension
-        assert.ok(extension)
+        extension = await getExtension()
         fixture = path.resolve(extension.extensionRoot, 'test/fixtures/testground')
     })
 
@@ -30,7 +27,6 @@ suite('Auto-build test suite', () => {
     teardown(async () => {
         await vscode.commands.executeCommand('workbench.action.closeAllEditors')
         if (extension) {
-            extension.manager.invalidateCache()
             extension.manager.rootFile = undefined
         }
 
@@ -43,8 +39,7 @@ suite('Auto-build test suite', () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.watch.files.ignore', undefined)
 
         if (path.basename(fixture) === 'testground') {
-            await sleep(250)
-            rimraf(fixture + '/*', (e) => {if (e) {console.error(e)}})
+            rimraf(fixture + '/{*,.vscode}', (e) => {if (e) {console.error(e)}})
             await sleep(500) // Required for pooling
         }
     })
diff --git a/test/suites/03_findroot.test.ts b/test/suites/03_findroot.test.ts
index ec6d365f6..4ba7a280f 100644
--- a/test/suites/03_findroot.test.ts
+++ b/test/suites/03_findroot.test.ts
@@ -3,21 +3,19 @@ import * as path from 'path'
 import rimraf from 'rimraf'
 import * as assert from 'assert'
 
-import { Extension, activate } from '../../src/main'
-import { runTest, writeTeX } from './utils'
+import { Extension } from '../../src/main'
+import { assertRoot, getExtension, runTest, writeTeX } from './utils'
 import { sleep } from '../utils/ciutils'
 
 suite('Find root file test suite', () => {
 
-    let extension: Extension | undefined
+    let extension: Extension
     const suiteName = path.basename(__filename).replace('.test.js', '')
     let fixture = path.resolve(__dirname, '../../../test/fixtures/testground')
     const fixtureName = 'testground'
 
     suiteSetup(async () => {
-        await vscode.commands.executeCommand('latex-workshop.activate')
-        extension = vscode.extensions.getExtension<ReturnType<typeof activate>>('James-Yu.latex-workshop')?.exports.extension
-        assert.ok(extension)
+        extension = await getExtension()
         fixture = path.resolve(extension.extensionRoot, 'test/fixtures/testground')
     })
 
@@ -33,27 +31,45 @@ suite('Find root file test suite', () => {
         }
 
         if (path.basename(fixture) === 'testground') {
-            await sleep(250)
-            rimraf(fixture + '/*', (e) => {if (e) {console.error(e)}})
+            rimraf(fixture + '/{*,.vscode}', (e) => {if (e) {console.error(e)}})
             await sleep(500) // Required for pooling
         }
     })
 
+
+    runTest({suiteName, fixtureName, testName: 'detect root with search.rootFiles.include'}, async () => {
+        await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
+        await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.include', ['alt/*.tex'])
+        await writeTeX('subfiletwomain', fixture)
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'sub/s.tex', rootName: 'alt/main.tex', extension})
+    })
+
+    runTest({suiteName, fixtureName, testName: 'detect root with search.rootFiles.exclude'}, async () => {
+        await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
+        await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.exclude', ['*.tex'])
+        await writeTeX('subfiletwomain', fixture)
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'sub/s.tex', rootName: 'alt/main.tex', extension})
+    })
+
+    runTest({suiteName, fixtureName, testName: 'auto-detect root with verbatim'}, async () => {
+        await writeTeX('subfileverbatim', fixture)
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'sub/s.tex', rootName: 'main.tex', extension})
+    })
+
     runTest({suiteName, fixtureName, testName: 'import package'}, async () => {
         await writeTeX('importthreelayer', fixture)
-        const doc = await vscode.workspace.openTextDocument(vscode.Uri.file(path.resolve(fixture, 'sub/subsub/sss/sss.tex')))
-        await vscode.window.showTextDocument(doc)
-        const root = await extension?.manager.findRoot()
-        assert.strictEqual(root, path.resolve(fixture, 'main.tex'))
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'sub/subsub/sss/sss.tex', rootName: 'main.tex', extension})
     })
 
     runTest({suiteName, fixtureName, testName: 'circular inclusion'}, async () => {
         await writeTeX('circularinclude', fixture)
-        const doc = await vscode.workspace.openTextDocument(vscode.Uri.file(path.resolve(fixture, 'alt.tex')))
-        await vscode.window.showTextDocument(doc)
-        const root = await extension?.manager.findRoot()
-        assert.strictEqual(root, path.join(fixture, 'main.tex'))
-        const includedTeX = extension?.manager.getIncludedTeX()
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'alt.tex', rootName: 'main.tex', extension})
+        const includedTeX = extension.manager.getIncludedTeX()
         assert.ok(includedTeX)
         assert.ok(
             includedTeX.includes(path.resolve(fixture, 'main.tex')) &&
diff --git a/test/suites/04_intellisense.test.ts b/test/suites/04_intellisense.test.ts
index 442aa10c2..cb085546a 100644
--- a/test/suites/04_intellisense.test.ts
+++ b/test/suites/04_intellisense.test.ts
@@ -3,21 +3,19 @@ import * as path from 'path'
 import rimraf from 'rimraf'
 import * as assert from 'assert'
 
-import { Extension, activate } from '../../src/main'
-import { getIntellisense, runTest, writeTeX } from './utils'
+import { Extension } from '../../src/main'
+import { getExtension, getIntellisense, runTest, writeTeX } from './utils'
 import { sleep } from '../utils/ciutils'
 
 suite('Intellisense test suite', () => {
 
-    let extension: Extension | undefined
+    let extension: Extension
     const suiteName = path.basename(__filename).replace('.test.js', '')
     let fixture = path.resolve(__dirname, '../../../test/fixtures/testground')
     const fixtureName = 'testground'
 
     suiteSetup(async () => {
-        await vscode.commands.executeCommand('latex-workshop.activate')
-        extension = vscode.extensions.getExtension<ReturnType<typeof activate>>('James-Yu.latex-workshop')?.exports.extension
-        assert.ok(extension)
+        extension = await getExtension()
         fixture = path.resolve(extension.extensionRoot, 'test/fixtures/testground')
     })
 
@@ -36,8 +34,7 @@ suite('Intellisense test suite', () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('intellisense.atSuggestionJSON.replace', undefined)
 
         if (path.basename(fixture) === 'testground') {
-            await sleep(250)
-            rimraf(fixture + '/*', (e) => {if (e) {console.error(e)}})
+            rimraf(fixture + '/{*,.vscode}', (e) => {if (e) {console.error(e)}})
             await sleep(500) // Required for pooling
         }
     })
diff --git a/test/suites/05_multiroot.test.ts b/test/suites/05_multiroot.test.ts
index c9061c5c2..6bbc6f954 100644
--- a/test/suites/05_multiroot.test.ts
+++ b/test/suites/05_multiroot.test.ts
@@ -3,22 +3,20 @@ import * as path from 'path'
 import rimraf from 'rimraf'
 import * as assert from 'assert'
 
-import { Extension, activate } from '../../src/main'
-import { runTest, writeTeX, assertBuild, touch, assertAutoBuild, writeTestFile, copyTestFile, getIntellisense } from './utils'
+import { Extension } from '../../src/main'
+import { runTest, writeTeX, assertBuild, touch, assertAutoBuild, writeTestFile, copyTestFile, getIntellisense, assertRoot, getExtension } from './utils'
 import { sleep } from '../utils/ciutils'
 
 suite('Multi-root workspace test suite', () => {
 
-    let extension: Extension | undefined
+    let extension: Extension
     const suiteName = path.basename(__filename).replace('.test.js', '')
     let fixture = path.resolve(__dirname, '../../../test/fixtures/multiroot')
     const fixtureName = 'multiroot'
 
     suiteSetup(async () => {
-        await vscode.commands.executeCommand('latex-workshop.activate')
-        extension = vscode.extensions.getExtension<ReturnType<typeof activate>>('James-Yu.latex-workshop')?.exports.extension
-        assert.ok(extension)
-        fixture = path.resolve(extension.extensionRoot, 'test/fixtures/multiroot')
+        extension = await getExtension()
+        fixture = path.resolve(extension.extensionRoot, 'test/fixtures/testground')
     })
 
     setup(async () => {
@@ -46,7 +44,6 @@ suite('Multi-root workspace test suite', () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.autoBuild.interval', undefined)
 
         if (path.basename(fixture) === 'multiroot') {
-            await sleep(250)
             rimraf(fixture + '/{A,B}/{*,.vscode}', (e) => {if (e) {console.error(e)}})
             await sleep(500) // Required for pooling
         }
@@ -104,7 +101,8 @@ suite('Multi-root workspace test suite', () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.include', ['alt/*.tex'])
         await writeTeX('subfiletwomain', fixture, {fileDir: 'A/'})
         touch(path.resolve(fixture, 'B', 'empty'))
-        await assertBuild({fixture, texFileName: 'A/sub/s.tex', pdfFileName: 'A/alt/main.pdf', extension})
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'A/sub/s.tex', rootName: 'A/alt/main.tex', extension})
     })
 
     runTest({suiteName, fixtureName, testName: 'detect root with search.rootFiles.exclude'}, async () => {
@@ -112,10 +110,11 @@ suite('Multi-root workspace test suite', () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.search.rootFiles.exclude', ['*.tex'])
         await writeTeX('subfiletwomain', fixture, {fileDir: 'A/'})
         touch(path.resolve(fixture, 'B', 'empty'))
-        await assertBuild({fixture, texFileName: 'A/sub/s.tex', pdfFileName: 'A/alt/main.pdf', extension})
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'A/sub/s.tex', rootName: 'A/alt/main.tex', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root A1'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root and build A1'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', true)
         await writeTeX('subfile', fixture, {fileDir: 'A/'})
@@ -123,7 +122,7 @@ suite('Multi-root workspace test suite', () => {
         await assertBuild({fixture, texFileName: 'A/sub/s.tex', pdfFileName: 'A/sub/s.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root A2'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root and build A2'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', false)
         await writeTeX('subfile', fixture, {fileDir: 'A/'})
@@ -131,7 +130,7 @@ suite('Multi-root workspace test suite', () => {
         await assertBuild({fixture, texFileName: 'A/sub/s.tex', pdfFileName: 'A/main.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root B1'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root and build B1'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', true)
         await writeTeX('subfile', fixture, {fileDir: 'B/'})
@@ -139,7 +138,7 @@ suite('Multi-root workspace test suite', () => {
         await assertBuild({fixture, texFileName: 'B/sub/s.tex', pdfFileName: 'B/sub/s.pdf', extension})
     })
 
-    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root B2'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto-detect subfile root and build B2'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', false)
         await writeTeX('subfile', fixture, {fileDir: 'B/'})
@@ -156,7 +155,7 @@ suite('Multi-root workspace test suite', () => {
         await assertAutoBuild({fixture, texFileName: 'A/sub/s.tex', pdfFileName: 'A/main.pdf', extension}, ['onSave'])
     })
 
-    runTest({only: true, suiteName, fixtureName, testName: 'auto build with subfiles and onSave 2'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'auto build with subfiles and onSave 2'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.autoBuild.run', 'onSave')
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.doNotPrompt', true)
         await vscode.workspace.getConfiguration('latex-workshop').update('latex.rootFile.useSubFile', true)
@@ -165,15 +164,16 @@ suite('Multi-root workspace test suite', () => {
         await assertAutoBuild({fixture, texFileName: 'A/sub/s.tex', pdfFileName: 'A/sub/s.pdf', extension}, ['onSave'])
     })
 
-    runTest({only: true, suiteName, fixtureName, testName: 'switching rootFile'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'switching rootFile'}, async () => {
         await writeTeX('main', fixture, {fileName: 'A/main.tex'})
         await writeTeX('main', fixture, {fileName: 'B/main.tex'})
-        await assertBuild({fixture, texFileName: 'A/main.tex', pdfFileName: 'A/main.pdf', extension, removepdf: true})
-        await assertBuild({fixture, texFileName: 'B/main.tex', pdfFileName: 'B/main.pdf', extension, removepdf: true})
-        await assertBuild({fixture, texFileName: 'A/main.tex', pdfFileName: 'A/main.pdf', extension})
+        assert.ok(extension)
+        await assertRoot({fixture, openName: 'A/main.tex', rootName: 'A/main.tex', extension})
+        await assertRoot({fixture, openName: 'B/main.tex', rootName: 'B/main.tex', extension})
+        await assertRoot({fixture, openName: 'A/main.tex', rootName: 'A/main.tex', extension})
     })
 
-    runTest({only: true, suiteName, fixtureName, testName: 'switching intellisense'}, async () => {
+    runTest({suiteName, fixtureName, testName: 'switching intellisense'}, async () => {
         await vscode.workspace.getConfiguration('latex-workshop').update('intellisense.citation.label', 'bibtex key')
         writeTestFile({fixture, fileName: 'A/main.tex'}, '\\documentclass{article}', '\\begin{document}', 'abc\\cite{}', '\\bibliography{A.bib}', '\\end{document}')
         writeTestFile({fixture, fileName: 'B/main.tex'}, '\\documentclass{article}', '\\begin{document}', 'abc\\cite{}', '\\bibliography{B.bib}', '\\end{document}')
diff --git a/test/suites/utils.ts b/test/suites/utils.ts
index d7bf8b52d..3d224f6dd 100644
--- a/test/suites/utils.ts
+++ b/test/suites/utils.ts
@@ -5,9 +5,16 @@ import * as glob from 'glob'
 import * as os from 'os'
 import * as assert from 'assert'
 
-import { Extension } from '../../src/main'
+import { Extension, activate } from '../../src/main'
 import { BuildFinished } from '../../src/components/eventbus'
 
+export async function getExtension() {
+    await vscode.commands.executeCommand('latex-workshop.activate')
+    const extension = vscode.extensions.getExtension<ReturnType<typeof activate>>('James-Yu.latex-workshop')?.exports.extension
+    assert.ok(extension)
+    return extension
+}
+
 export function touch(filePath: string) {
     fs.closeSync(fs.openSync(filePath, 'a'))
 }
@@ -99,7 +106,7 @@ type AssertBuildOption = {
     fixture: string,
     texFileName: string,
     pdfFileName: string,
-    extension?: Extension,
+    extension: Extension,
     build?: () => unknown,
     nobuild?: boolean,
     removepdf?: boolean
@@ -110,15 +117,17 @@ export async function assertBuild(option: AssertBuildOption) {
     const pdfFilePath = path.join(option.fixture, option.pdfFileName)
     const doc = await vscode.workspace.openTextDocument(texFilePath)
     await vscode.window.showTextDocument(doc)
-    await option.extension?.manager.findRoot()
+    await option.extension.manager.findRoot()
     if (option.build) {
         await option.build()
     } else {
-        await vscode.commands.executeCommand('latex-workshop.build')
+        await option.extension.commander.build()
     }
 
     const files = glob.sync('**/**.pdf', { cwd: option.fixture })
     assert.strictEqual(files.map(file => path.resolve(option.fixture, file)).join(','), option.pdfFileName === '' ? option.pdfFileName : pdfFilePath)
+    await sleep(500) // Wait for post-build processing
+
     if (option.removepdf) {
         files.forEach(async file => {
             if (fs.existsSync(path.join(option.fixture, file))) {
@@ -155,17 +164,35 @@ export async function assertAutoBuild(option: AssertBuildOption, mode?: ('skipFi
         files = glob.sync('**/**.pdf', { cwd: option.fixture })
         assert.strictEqual(files.map(file => path.resolve(option.fixture, file)).join(','), path.resolve(option.fixture, option.pdfFileName))
     }
+    await sleep(500) // Wait for post-build processing
 }
 
-export async function waitBuild(extension?: Extension) {
+export async function waitBuild(extension: Extension) {
     return new Promise<void>((resolve, _) => {
-        const disposable = extension?.eventBus.on(BuildFinished, () => {
+        const disposable = extension.eventBus.on(BuildFinished, () => {
             resolve()
             disposable?.dispose()
         })
     })
 }
 
+type AssertRootOption = {
+    fixture: string,
+    openName: string,
+    rootName: string,
+    extension: Extension
+}
+
+export async function assertRoot(option: AssertRootOption) {
+    await vscode.commands.executeCommand('latex-workshop.activate')
+    const openFilePath = vscode.Uri.file(path.join(option.fixture, option.openName))
+    const rootFilePath = path.join(option.fixture, option.rootName)
+    const doc = await vscode.workspace.openTextDocument(openFilePath)
+    await vscode.window.showTextDocument(doc)
+    const root = await option.extension.manager.findRoot()
+    assert.strictEqual(root, rootFilePath)
+}
+
 type WriteTeXType = 'main' | 'makeindex' | 'makesubfileindex' | 'magicprogram' | 'magicoption' | 'magicroot' | 'magicinvalidprogram' |
     'subfile' | 'subfileverbatim' | 'subfiletwomain' | 'subfilethreelayer' | 'importthreelayer' | 'bibtex' |
     'input' | 'inputmacro' | 'inputfromfolder' | 'circularinclude' | 'intellisense' | 'structure' | 'linter'
@@ -263,8 +290,8 @@ export async function writeTeX(type: WriteTeXType, fixture: string, payload?: {f
     await sleep(250)
 }
 
-export function getIntellisense(doc: vscode.TextDocument, pos: vscode.Position, extension?: Extension, atSuggestion = false) {
-    const completer = atSuggestion ? extension?.atSuggestionCompleter : extension?.completer
+export function getIntellisense(doc: vscode.TextDocument, pos: vscode.Position, extension: Extension, atSuggestion = false) {
+    const completer = atSuggestion ? extension.atSuggestionCompleter : extension.completer
     return completer?.provideCompletionItems(
         doc, pos, new vscode.CancellationTokenSource().token, {
             triggerKind: vscode.CompletionTriggerKind.Invoke,