diff --git a/.github/workflows/jest.yml b/.github/workflows/jest.yml
index 0223df31c..ea29486da 100644
--- a/.github/workflows/jest.yml
+++ b/.github/workflows/jest.yml
@@ -5,12 +5,12 @@ on:
   pull_request:
     paths:
       - "binderhub/static/js/**"
-      - "js/packages/binderhub-client/**"
+      - "js/**"
       - ".github/workflows/jest.yml"
   push:
     paths:
       - "binderhub/static/js/**"
-      - "js/packages/binderhub-client/**"
+      - "js/**"
       - ".github/workflows/jest.yml"
     branches-ignore:
       - "dependabot/**"
diff --git a/binderhub/repoproviders.py b/binderhub/repoproviders.py
index 538a88c3d..799901545 100644
--- a/binderhub/repoproviders.py
+++ b/binderhub/repoproviders.py
@@ -226,8 +226,13 @@ class FakeProvider(RepoProvider):
         "displayName": "Fake",
         "id": "fake",
         "enabled": False,
-        "spec": {"validateRegex": ".*"},
-        "repo": {"label": "Fake Repo", "placeholder": "", "urlEncode": False},
+        "spec": {"validateRegex": ".+"},
+        "detect": {"regex": "(?<repo>.+)"},
+        "repo": {
+            "label": "Fake Repo",
+            "placeholder": "example: fake",
+            "urlEncode": False,
+        },
         "ref": {
             "enabled": False,
         },
diff --git a/js/packages/binderhub-react-components/babel.config.js b/js/packages/binderhub-react-components/babel.config.js
new file mode 100644
index 000000000..898ec947a
--- /dev/null
+++ b/js/packages/binderhub-react-components/babel.config.js
@@ -0,0 +1,6 @@
+module.exports = {
+  presets: [
+    ["@babel/preset-env", { targets: { node: "current" } }],
+    ["@babel/preset-react", { runtime: "automatic" }],
+  ],
+};
diff --git a/js/packages/binderhub-react-components/package.json b/js/packages/binderhub-react-components/package.json
index ee17021b2..f242f327c 100644
--- a/js/packages/binderhub-react-components/package.json
+++ b/js/packages/binderhub-react-components/package.json
@@ -7,8 +7,13 @@
   },
   "scripts": {
     "build": "esbuild src/*.jsx --loader:.ico=dataurl --bundle --external:react --outdir=dist",
-    "lint": "eslint binderhub/static/js js",
-    "test": "echo \"Error: no test specified\" && exit 1"
+    "test": "jest"
+  },
+  "jest": {
+    "testEnvironment": "jsdom",
+    "setupFilesAfterEnv": [
+      "<rootDir>/../../../setupTests.js"
+    ]
   },
   "repository": {
     "type": "git",
@@ -24,6 +29,8 @@
   },
   "homepage": "https://github.com/jupyterhub/binderhub#readme",
   "devDependencies": {
+    "@babel/preset-env": "^7.28.3",
+    "@babel/preset-react": "^7.27.1",
     "esbuild": "^0.25.6",
     "eslint": "^9.31.0"
   },
diff --git a/js/packages/binderhub-react-components/src/LinkGenerator.jsx b/js/packages/binderhub-react-components/src/LinkGenerator.jsx
index 6288b45c3..40b310bc7 100644
--- a/js/packages/binderhub-react-components/src/LinkGenerator.jsx
+++ b/js/packages/binderhub-react-components/src/LinkGenerator.jsx
@@ -201,6 +201,8 @@ export function LinkGenerator({
                 const results = re.exec(repo);
                 if (results !== null && results.groups && results.groups.repo) {
                   setRepo(results.groups.repo);
+                } else {
+                  setRepo("");
                 }
               } else {
                 setRepo(e.target.value);
diff --git a/js/packages/binderhub-react-components/src/LinkGenerator.test.jsx b/js/packages/binderhub-react-components/src/LinkGenerator.test.jsx
new file mode 100644
index 000000000..677b400a5
--- /dev/null
+++ b/js/packages/binderhub-react-components/src/LinkGenerator.test.jsx
@@ -0,0 +1,77 @@
+import { render, screen } from "@testing-library/react";
+import userEvent from "@testing-library/user-event";
+import { LinkGenerator } from "./LinkGenerator";
+import { useState } from "react";
+
+const mockProviders = window.pageConfig.repoProviders;
+
+const publicBaseUrl = new URL("https://example.org/");
+
+function TestLinkGeneratorWrapper() {
+  const [selectedProvider, setSelectedProvider] = useState(mockProviders[0]);
+  const [repo, setRepo] = useState("");
+  const [reference, setReference] = useState("");
+  const [urlPath, setUrlPath] = useState("");
+  const [isLaunching, setIsLaunching] = useState(false);
+
+  return (
+    <LinkGenerator
+      providers={mockProviders}
+      publicBaseUrl={publicBaseUrl}
+      selectedProvider={selectedProvider}
+      setSelectedProvider={setSelectedProvider}
+      repo={repo}
+      setRepo={setRepo}
+      reference={reference}
+      setReference={setReference}
+      urlPath={urlPath}
+      setUrlPath={setUrlPath}
+      isLaunching={isLaunching}
+      setIsLaunching={setIsLaunching}
+    />
+  );
+}
+
+describe("LinkGenerator", () => {
+  it("updates launch-url from repo, ref and file", async () => {
+    const user = userEvent.setup();
+    render(<TestLinkGeneratorWrapper />);
+
+    // This lookup uses the aria label
+    const repoInput = screen.getByRole("textbox", {
+      name: "Enter repository URL",
+    });
+    await user.type(repoInput, "my-org/my-repo");
+
+    const refInput = screen.getByLabelText("Git ref (branch, tag, or commit)");
+    await user.type(refInput, "my-branch");
+
+    const pathInput = screen.getByLabelText("File to open (in JupyterLab)");
+    await user.type(pathInput, "notebooks/test.ipynb");
+
+    const expectedUrl =
+      "https://example.org/v2/gh/my-org/my-repo/my-branch?urlpath=%2Fdoc%2Ftree%2Fnotebooks%2Ftest.ipynb";
+    expect(screen.getByTestId("launch-url").textContent).toBe(expectedUrl);
+  });
+
+  it("renders initial placeholder and restores it if repo is deleted", async () => {
+    const user = userEvent.setup();
+    render(<TestLinkGeneratorWrapper />);
+
+    const defaultLaunchUrl =
+      "Fill in the fields to see a URL for sharing your Binder.";
+    expect(screen.getByTestId("launch-url").textContent).toBe(defaultLaunchUrl);
+
+    const repoInput = screen.getByRole("textbox", {
+      name: "Enter repository URL",
+    });
+    await user.type(repoInput, "x");
+
+    expect(screen.getByTestId("launch-url").textContent).toBe(
+      "https://example.org/v2/gh/x/HEAD",
+    );
+
+    await user.type(repoInput, "{backspace}");
+    expect(screen.getByTestId("launch-url").textContent).toBe(defaultLaunchUrl);
+  });
+});
diff --git a/testing/local-binder-mocked-hub/binderhub_config.py b/testing/local-binder-mocked-hub/binderhub_config.py
index 142b36c34..e8ead12e7 100644
--- a/testing/local-binder-mocked-hub/binderhub_config.py
+++ b/testing/local-binder-mocked-hub/binderhub_config.py
@@ -14,7 +14,7 @@
 c.BinderHub.use_registry = True
 c.BinderHub.registry_class = FakeRegistry
 c.BinderHub.builder_required = False
-c.BinderHub.repo_providers = {"gh": FakeProvider}
+c.BinderHub.repo_providers = {"fake": FakeProvider}
 c.BinderHub.build_class = FakeBuild
 
 # Uncomment the following line to enable BinderHub's API only mode