diff --git a/src/browser/renderer/dom/DomRendererRowFactory.test.ts b/src/browser/renderer/dom/DomRendererRowFactory.test.ts
index b7c60e8f3..6ca84569a 100644
--- a/src/browser/renderer/dom/DomRendererRowFactory.test.ts
+++ b/src/browser/renderer/dom/DomRendererRowFactory.test.ts
@@ -15,10 +15,8 @@ import { MockCoreService, MockDecorationService, MockOptionsService, createCellD
 import { MockCharacterJoinerService, MockCoreBrowserService, MockThemeService } from 'browser/TestUtils.test';
 import { TestWidthCache } from 'browser/renderer/dom/WidthCache.test';
 
-const dom = new jsdom.JSDOM('');
 const TEST_STRING_CACHE = new BufferLineStringCache();
 
-
 describe('DomRendererRowFactory', () => {
   let dom: jsdom.JSDOM;
   let rowFactory: DomRendererRowFactory;
diff --git a/src/common/buffer/Buffer.test.ts b/src/common/buffer/Buffer.test.ts
index 5a5cb3522..ae086554e 100644
--- a/src/common/buffer/Buffer.test.ts
+++ b/src/common/buffer/Buffer.test.ts
@@ -17,15 +17,25 @@ const INIT_ROWS = 24;
 const INIT_SCROLLBACK = 1000;
 const TEST_STRING_CACHE = new BufferLineStringCache();
 
+class TestBuffer extends Buffer {
+  public getStringCache(): BufferLineStringCache {
+    return (this as unknown as { _stringCache: BufferLineStringCache })._stringCache;
+  }
+
+  public getStringCacheClearTimeout(): unknown {
+    return (this.getStringCache() as unknown as { _clearTimeout: { value: unknown } })._clearTimeout.value;
+  }
+}
+
 describe('Buffer', () => {
   let optionsService: MockOptionsService;
   let bufferService: MockBufferService;
-  let buffer: Buffer;
+  let buffer: TestBuffer;
 
   beforeEach(() => {
     optionsService = new MockOptionsService({ scrollback: INIT_SCROLLBACK });
     bufferService = new MockBufferService(INIT_COLS, INIT_ROWS);
-    buffer = new Buffer(true, optionsService, bufferService, new MockLogService());
+    buffer = new TestBuffer(true, optionsService, bufferService, new MockLogService());
   });
 
   describe('constructor', () => {
@@ -153,7 +163,7 @@ describe('Buffer', () => {
 
       describe('no scrollback', () => {
         it('should trim from the top of the buffer when the cursor reaches the bottom', () => {
-          buffer = new Buffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
+          buffer = new TestBuffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
           assert.equal(buffer.lines.maxLength, INIT_ROWS);
           buffer.y = INIT_ROWS - 1;
           buffer.fillViewportRows();
@@ -1056,7 +1066,7 @@ describe('Buffer', () => {
   describe('buffer marked to have no scrollback', () => {
     it('should always have a scrollback of 0', () => {
       // Test size on initialization
-      buffer = new Buffer(false, new MockOptionsService({ scrollback: 1000 }), bufferService, new MockLogService());
+      buffer = new TestBuffer(false, new MockOptionsService({ scrollback: 1000 }), bufferService, new MockLogService());
       buffer.fillViewportRows();
       assert.equal(buffer.lines.maxLength, INIT_ROWS);
       // Test size on buffer increase
@@ -1070,7 +1080,7 @@ describe('Buffer', () => {
 
   describe('addMarker', () => {
     it('should adjust a marker line when the buffer is trimmed', () => {
-      buffer = new Buffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
+      buffer = new TestBuffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
       buffer.fillViewportRows();
       const marker = buffer.addMarker(buffer.lines.length - 1);
       assert.equal(marker.line, buffer.lines.length - 1);
@@ -1078,7 +1088,7 @@ describe('Buffer', () => {
       assert.equal(marker.line, buffer.lines.length - 2);
     });
     it('should dispose of a marker if it is trimmed off the buffer', () => {
-      buffer = new Buffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
+      buffer = new TestBuffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
       buffer.fillViewportRows();
       assert.equal(buffer.markers.length, 0);
       const marker = buffer.addMarker(0);
@@ -1090,7 +1100,7 @@ describe('Buffer', () => {
     });
     it('should call onDispose', () => {
       const eventStack: string[] = [];
-      buffer = new Buffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
+      buffer = new TestBuffer(true, new MockOptionsService({ scrollback: 0 }), bufferService, new MockLogService());
       buffer.fillViewportRows();
       assert.equal(buffer.markers.length, 0);
       const marker = buffer.addMarker(0);
@@ -1203,15 +1213,15 @@ describe('Buffer', () => {
         assert.equal(buffer.translateBufferLineToString(0, false), `a${' '.repeat(INIT_COLS - 1)}`);
         assert.equal(buffer.translateBufferLineToString(1, false), `b${' '.repeat(INIT_COLS - 1)}`);
 
-        const cache = (buffer as any)._stringCache;
+        const cache = buffer.getStringCache();
         assert.equal(cache.entries.size, 2);
-        const previousTimer = (cache as any)._clearTimeout.value;
-        assert.notEqual(previousTimer, undefined);
+        const previousTimer = buffer.getStringCacheClearTimeout();
+        assert.ok(previousTimer !== undefined);
 
         // Another translation should refresh the same shared timer, not create a second queue.
         assert.equal(buffer.translateBufferLineToString(0, false), `a${' '.repeat(INIT_COLS - 1)}`);
-        assert.notEqual((cache as any)._clearTimeout.value, undefined);
-        assert.notEqual((cache as any)._clearTimeout.value, previousTimer);
+        assert.ok(buffer.getStringCacheClearTimeout() !== undefined);
+        assert.notEqual(buffer.getStringCacheClearTimeout(), previousTimer);
 
         for (const timeout of scheduledTimeouts.values()) {
           timeout();
@@ -1219,7 +1229,7 @@ describe('Buffer', () => {
         scheduledTimeouts.clear();
 
         assert.equal(cache.entries.size, 0);
-        assert.equal((cache as any)._clearTimeout.value, undefined);
+        assert.equal(buffer.getStringCacheClearTimeout(), undefined);
 
         // Cache entries should be recreated lazily after a timer-based reset.
         assert.equal(buffer.translateBufferLineToString(0, false), `a${' '.repeat(INIT_COLS - 1)}`);
@@ -1235,13 +1245,13 @@ describe('Buffer', () => {
       buffer.lines.get(0)!.setCell(0, createCellData(0, 'a', 1));
       buffer.translateBufferLineToString(0, false);
 
-      const cache = (buffer as any)._stringCache;
+      const cache = buffer.getStringCache();
       assert.equal(cache.entries.size, 1);
-      assert.notEqual((cache as any)._clearTimeout.value, undefined);
+      assert.ok(buffer.getStringCacheClearTimeout() !== undefined);
 
       buffer.clear();
       assert.equal(cache.entries.size, 0);
-      assert.equal((cache as any)._clearTimeout.value, undefined);
+      assert.equal(buffer.getStringCacheClearTimeout(), undefined);
 
       buffer.fillViewportRows();
       buffer.lines.get(0)!.setCell(0, createCellData(0, 'b', 1));
@@ -1250,7 +1260,7 @@ describe('Buffer', () => {
 
       buffer.resize(INIT_COLS - 1, INIT_ROWS);
       assert.equal(cache.entries.size, 0);
-      assert.equal((cache as any)._clearTimeout.value, undefined);
+      assert.equal(buffer.getStringCacheClearTimeout(), undefined);
     });
   });