diff --git a/src/node-file-trace.ts b/src/node-file-trace.ts
index 2623a83d..40c92f0a 100644
--- a/src/node-file-trace.ts
+++ b/src/node-file-trace.ts
@@ -232,7 +232,7 @@ export class Job {
     // keep backtracking for realpath, emitting folder symlinks within base
     if (!inPath(path, this.base))
       return path;
-    return this.realpath(dirname(path), parent, seen) + sep + basename(path);
+    return join(this.realpath(dirname(path), parent, seen), basename(path));
   }
 
   emitFile (path: string, reason: string, parent?: string, isRealpath = false) {
diff --git a/test/unit.test.js b/test/unit.test.js
index c97a15b5..76fa70b6 100644
--- a/test/unit.test.js
+++ b/test/unit.test.js
@@ -5,15 +5,20 @@ const { nodeFileTrace } = require('../out/node-file-trace');
 global._unit = true;
 
 const skipOnWindows = ['yarn-workspaces', 'yarn-workspaces-base-root', 'yarn-workspace-esm', 'asset-symlink', 'require-symlink'];
-const setBaseToRoot = ['yarn-workspaces-base-root'];
+const unitTestDirs = fs.readdirSync(join(__dirname, 'unit'));
+const unitTests = [
+  ...unitTestDirs.map(testName => ({testName, isRoot: false})),
+  ...unitTestDirs.map(testName => ({testName, isRoot: true})),
+];
 
-for (const unitTest of fs.readdirSync(join(__dirname, 'unit'))) {
-  if (process.platform === 'win32' && skipOnWindows.includes(unitTest)) {
-    console.log('skipping symlink test on Windows: ' + unitTest);
+for (const { testName, isRoot } of unitTests) {
+  const testSuffix = `${testName} from ${isRoot ? 'root' : 'cwd'}`;
+  if (process.platform === 'win32' && (isRoot || skipOnWindows.includes(testName))) {
+    console.log(`Skipping unit test on Windows: ${testSuffix}`);
     continue;
-  }
-  it(`should correctly trace ${unitTest}`, async () => {
-    const unitPath = join(__dirname, 'unit', unitTest);
+  };
+  it(`should correctly trace ${testSuffix}`, async () => {
+    const unitPath = join(__dirname, 'unit', testName);
 
     // We mock readFile because when node-file-trace is integrated into @now/node
     // this is the hook that triggers TypeScript compilation. So if this doesn't
@@ -25,26 +30,25 @@ for (const unitTest of fs.readdirSync(join(__dirname, 'unit'))) {
 
     let inputFileName = "input.js";
 
-    if (unitTest === "tsx-input") {
+    if (testName === "tsx-input") {
       inputFileName = "input.tsx";
     }
 
-    const isRoot = setBaseToRoot.includes(unitTest);
-
     const { fileList, reasons } = await nodeFileTrace([join(unitPath, inputFileName)], {
       base: isRoot ? '/' : `${__dirname}/../`,
       processCwd: unitPath,
       paths: {
-        dep: 'test/unit/esm-paths/esm-dep.js',
-        'dep/': 'test/unit/esm-paths-trailer/'
+        dep: `${__dirname}/../test/unit/esm-paths/esm-dep.js`,
+        'dep/': `${__dirname}/../test/unit/esm-paths-trailer/`
       },
-      exportsOnly: unitTest.startsWith('exports-only'),
+      exportsOnly: testName.startsWith('exports-only'),
       ts: true,
       log: true,
       // disable analysis for basic-analysis unit tests
-      analysis: !unitTest.startsWith('basic-analysis'),
+      analysis: !testName.startsWith('basic-analysis'),
       mixedModules: true,
-      ignore: '**/actual.js',
+      // Ignore unit test output "actual.js", and ignore GitHub Actions preinstalled packages
+      ignore: (str) => str.endsWith('/actual.js') || str.startsWith('usr/local'),
       readFile: readFileMock
     });
     let expected;
@@ -73,7 +77,7 @@ for (const unitTest of fs.readdirSync(join(__dirname, 'unit'))) {
       throw e;
     }
 
-    if (unitTest === "tsx-input") {
+    if (testName === "tsx-input") {
       expect(readFileMock.mock.calls.length).toBe(2);
     }
   });
diff --git a/test/unit/yarn-workspaces-base-root/.gitignore b/test/unit/yarn-workspaces-base-root/.gitignore
deleted file mode 100644
index 864b66cd..00000000
--- a/test/unit/yarn-workspaces-base-root/.gitignore
+++ /dev/null
@@ -1,2 +0,0 @@
-# include node_modules to test the symlinks
-!node_modules 
diff --git a/test/unit/yarn-workspaces-base-root/input.js b/test/unit/yarn-workspaces-base-root/input.js
deleted file mode 100644
index d757ce0b..00000000
--- a/test/unit/yarn-workspaces-base-root/input.js
+++ /dev/null
@@ -1 +0,0 @@
-require('x');
diff --git a/test/unit/yarn-workspaces-base-root/node_modules/x b/test/unit/yarn-workspaces-base-root/node_modules/x
deleted file mode 120000
index 8bace9bb..00000000
--- a/test/unit/yarn-workspaces-base-root/node_modules/x
+++ /dev/null
@@ -1 +0,0 @@
-../packages/x
\ No newline at end of file
diff --git a/test/unit/yarn-workspaces-base-root/output.js b/test/unit/yarn-workspaces-base-root/output.js
deleted file mode 100644
index 7864f4c5..00000000
--- a/test/unit/yarn-workspaces-base-root/output.js
+++ /dev/null
@@ -1,8 +0,0 @@
-[
-  "package.json",
-  "test/unit/yarn-workspaces-base-root/input.js",
-  "test/unit/yarn-workspaces-base-root/node_modules/x",
-  "test/unit/yarn-workspaces-base-root/packages/x/dep.js",
-  "test/unit/yarn-workspaces-base-root/packages/x/main.ts",
-  "test/unit/yarn-workspaces-base-root/packages/x/package.json"
-]
\ No newline at end of file
diff --git a/test/unit/yarn-workspaces-base-root/packages/x/dep.js b/test/unit/yarn-workspaces-base-root/packages/x/dep.js
deleted file mode 100644
index 888cae37..00000000
--- a/test/unit/yarn-workspaces-base-root/packages/x/dep.js
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = 42;
diff --git a/test/unit/yarn-workspaces-base-root/packages/x/main.ts b/test/unit/yarn-workspaces-base-root/packages/x/main.ts
deleted file mode 100644
index 3e5530eb..00000000
--- a/test/unit/yarn-workspaces-base-root/packages/x/main.ts
+++ /dev/null
@@ -1 +0,0 @@
-module.exports = require('./dep.js');
diff --git a/test/unit/yarn-workspaces-base-root/packages/x/package.json b/test/unit/yarn-workspaces-base-root/packages/x/package.json
deleted file mode 100644
index 528005c9..00000000
--- a/test/unit/yarn-workspaces-base-root/packages/x/package.json
+++ /dev/null
@@ -1,3 +0,0 @@
-{
-  "main": "./main"
-}