diff --git a/extensions/ql-vscode/src/common/unzip.ts b/extensions/ql-vscode/src/common/unzip.ts
index acd24510f..77052fe52 100644
--- a/extensions/ql-vscode/src/common/unzip.ts
+++ b/extensions/ql-vscode/src/common/unzip.ts
@@ -28,12 +28,7 @@ export function readZipEntries(zipFile: ZipFile): Promise<ZipEntry[]> {
 
     zipFile.readEntry();
     zipFile.on("entry", (entry: ZipEntry) => {
-      if (/\/$/.test(entry.fileName)) {
-        // Directory file names end with '/'
-        // We don't need to do anything for directories.
-      } else {
-        files.push(entry);
-      }
+      files.push(entry);
 
       zipFile.readEntry();
     });
diff --git a/extensions/ql-vscode/test/unit-tests/common/unzip.test.ts b/extensions/ql-vscode/test/unit-tests/common/unzip.test.ts
new file mode 100644
index 000000000..931517fac
--- /dev/null
+++ b/extensions/ql-vscode/test/unit-tests/common/unzip.test.ts
@@ -0,0 +1,113 @@
+import { resolve } from "path";
+import {
+  excludeDirectories,
+  openZip,
+  openZipBuffer,
+  readZipEntries,
+} from "../../../src/common/unzip";
+
+const zipWithSingleFilePath = resolve(
+  __dirname,
+  "../../vscode-tests/no-workspace/data/archive-filesystem-provider-test/single_file.zip",
+);
+const zipWithFolderPath = resolve(
+  __dirname,
+  "../../vscode-tests/no-workspace/data/archive-filesystem-provider-test/zip_with_folder.zip",
+);
+
+describe("openZip", () => {
+  it("can open a zip file", async () => {
+    const zipFile = await openZip(zipWithFolderPath, {
+      lazyEntries: false,
+    });
+
+    expect(zipFile.entryCount).toEqual(8);
+  });
+});
+
+describe("readZipEntries", () => {
+  it("can read the entries when there is a single file", async () => {
+    const zipFile = await openZip(zipWithSingleFilePath, {
+      lazyEntries: true,
+    });
+    const entries = await readZipEntries(zipFile);
+
+    expect(entries.map((entry) => entry.fileName).sort()).toEqual([
+      "src_archive/",
+      "src_archive/aFileName.txt",
+    ]);
+  });
+
+  it("can read the entries when there are multiple folders", async () => {
+    const zipFile = await openZip(zipWithFolderPath, {
+      lazyEntries: true,
+    });
+    const entries = await readZipEntries(zipFile);
+
+    expect(entries.map((entry) => entry.fileName).sort()).toEqual([
+      "__MACOSX/._folder1",
+      "__MACOSX/folder1/._textFile.txt",
+      "__MACOSX/folder1/._textFile2.txt",
+      "folder1/",
+      "folder1/folder2/",
+      "folder1/folder2/textFile3.txt",
+      "folder1/textFile.txt",
+      "folder1/textFile2.txt",
+    ]);
+  });
+});
+
+describe("excludeDirectories", () => {
+  it("excludes directories when there is a single file", async () => {
+    const zipFile = await openZip(zipWithSingleFilePath, {
+      lazyEntries: true,
+    });
+    const entries = await readZipEntries(zipFile);
+    const entriesWithoutDirectories = excludeDirectories(entries);
+
+    expect(
+      entriesWithoutDirectories.map((entry) => entry.fileName).sort(),
+    ).toEqual(["src_archive/aFileName.txt"]);
+  });
+
+  it("excludes directories when there are multiple folders", async () => {
+    const zipFile = await openZip(zipWithFolderPath, {
+      lazyEntries: true,
+    });
+    const entries = await readZipEntries(zipFile);
+    const entriesWithoutDirectories = excludeDirectories(entries);
+
+    expect(
+      entriesWithoutDirectories.map((entry) => entry.fileName).sort(),
+    ).toEqual([
+      "__MACOSX/._folder1",
+      "__MACOSX/folder1/._textFile.txt",
+      "__MACOSX/folder1/._textFile2.txt",
+      "folder1/folder2/textFile3.txt",
+      "folder1/textFile.txt",
+      "folder1/textFile2.txt",
+    ]);
+  });
+});
+
+describe("openZipBuffer", () => {
+  it("can read an entry in the zip file", async () => {
+    const zipFile = await openZip(zipWithFolderPath, {
+      lazyEntries: true,
+      autoClose: false,
+    });
+    const entries = await readZipEntries(zipFile);
+
+    const entry = entries.find(
+      (entry) => entry.fileName === "folder1/textFile.txt",
+    );
+    expect(entry).toBeDefined();
+    if (!entry) {
+      return;
+    }
+
+    const buffer = await openZipBuffer(zipFile, entry);
+    expect(buffer).toHaveLength(12);
+    expect(buffer.toString("utf8")).toEqual("I am a text\n");
+  });
+});