diff --git a/__mocks__/__tests__/gatsby-plugin-firebase/auth.signInAnonymously.test.js b/__mocks__/__tests__/gatsby-plugin-firebase/auth.signInAnonymously.test.js
new file mode 100644
index 00000000..d159d44e
--- /dev/null
+++ b/__mocks__/__tests__/gatsby-plugin-firebase/auth.signInAnonymously.test.js
@@ -0,0 +1,35 @@
+import FirebaseStub, { AuthConstants } from '../../gatsby-plugin-firebase';
+
+test('sets current user to anonymous user 1', async () => {
+  await FirebaseStub.auth().signInAnonymously();
+
+  const { currentUser } = FirebaseStub.auth();
+  expect(currentUser).toBeTruthy();
+  expect(currentUser.uid).toEqual(AuthConstants.anonymousUser1.uid);
+});
+
+test('calls onAuthStateChanged observer with anonymous user 1', async () => {
+  let user = null;
+  let error = null;
+  FirebaseStub.auth().onAuthStateChanged(
+    (_user) => {
+      user = _user;
+    },
+    (_error) => {
+      error = _error;
+    },
+  );
+
+  await FirebaseStub.auth().signInAnonymously();
+
+  expect(user).toBeTruthy();
+  expect(user.uid).toEqual(AuthConstants.anonymousUser1.uid);
+  expect(error).toBeNull();
+});
+
+test('returns anonymous user 1', async () => {
+  const user = await FirebaseStub.auth().signInAnonymously();
+
+  expect(user).toBeTruthy();
+  expect(user.uid).toEqual(AuthConstants.anonymousUser1.uid);
+});
diff --git a/__mocks__/__tests__/gatsby-plugin-firebase/auth.signInWithPopup.test.js b/__mocks__/__tests__/gatsby-plugin-firebase/auth.signInWithPopup.test.js
new file mode 100644
index 00000000..e20cd1ca
--- /dev/null
+++ b/__mocks__/__tests__/gatsby-plugin-firebase/auth.signInWithPopup.test.js
@@ -0,0 +1,54 @@
+import FirebaseStub, { AuthConstants } from '../../gatsby-plugin-firebase';
+
+describe('with Google auth provider', () => {
+  test('sets current user to Google user 3', async () => {
+    await FirebaseStub.auth().signInWithPopup(
+      new FirebaseStub.auth.GoogleAuthProvider(),
+    );
+
+    const { currentUser } = FirebaseStub.auth();
+    expect(currentUser).toBeTruthy();
+    expect(currentUser.uid).toEqual(AuthConstants.googleUser3.uid);
+  });
+
+  test('sets current user provider data', async () => {
+    const provider = new FirebaseStub.auth.GoogleAuthProvider();
+    await FirebaseStub.auth().signInWithPopup(provider);
+
+    const { currentUser } = FirebaseStub.auth();
+    expect(currentUser).toBeTruthy();
+    expect(currentUser.providerData).toBeTruthy();
+    expect(currentUser.providerData).toHaveLength(1);
+    expect(currentUser.providerData[0].providerId).toEqual(provider.providerId);
+  });
+
+  test('calls onAuthStateChanged observer with Google user 3', async () => {
+    let user = null;
+    let error = null;
+    FirebaseStub.auth().onAuthStateChanged(
+      (_user) => {
+        user = _user;
+      },
+      (_error) => {
+        error = _error;
+      },
+    );
+
+    await FirebaseStub.auth().signInWithPopup(
+      new FirebaseStub.auth.GoogleAuthProvider(),
+    );
+
+    expect(user).toBeTruthy();
+    expect(user.uid).toEqual(AuthConstants.googleUser3.uid);
+    expect(error).toBeNull();
+  });
+
+  test('returns Google user 3', async () => {
+    const user = await FirebaseStub.auth().signInWithPopup(
+      new FirebaseStub.auth.GoogleAuthProvider(),
+    );
+
+    expect(user).toBeTruthy();
+    expect(user.uid).toEqual(AuthConstants.googleUser3.uid);
+  });
+});
diff --git a/__mocks__/__tests__/gatsby-plugin-firebase/auth.signOut.test.js b/__mocks__/__tests__/gatsby-plugin-firebase/auth.signOut.test.js
new file mode 100644
index 00000000..06bd830b
--- /dev/null
+++ b/__mocks__/__tests__/gatsby-plugin-firebase/auth.signOut.test.js
@@ -0,0 +1,29 @@
+import FirebaseStub from '../../gatsby-plugin-firebase';
+
+test('sets current user to null', async () => {
+  await FirebaseStub.auth().signInAnonymously();
+
+  await FirebaseStub.auth().signOut();
+
+  const { currentUser } = FirebaseStub.auth();
+  expect(currentUser).toBeNull();
+});
+
+test('calls onAuthStateChanged observer with null', async () => {
+  let user = null;
+  let error = null;
+  FirebaseStub.auth().onAuthStateChanged(
+    (_user) => {
+      user = _user;
+    },
+    (_error) => {
+      error = _error;
+    },
+  );
+  await FirebaseStub.auth().signInAnonymously();
+
+  await FirebaseStub.auth().signOut();
+
+  expect(user).toBeNull();
+  expect(error).toBeNull();
+});
diff --git a/__mocks__/__tests__/gatsby-plugin-firebase/auth.test.js b/__mocks__/__tests__/gatsby-plugin-firebase/auth.test.js
index ca18050d..2ffd0aa3 100644
--- a/__mocks__/__tests__/gatsby-plugin-firebase/auth.test.js
+++ b/__mocks__/__tests__/gatsby-plugin-firebase/auth.test.js
@@ -1,4 +1,4 @@
-import FirebaseStub, { AuthConstants } from '../../gatsby-plugin-firebase';
+import FirebaseStub from '../../gatsby-plugin-firebase';
 
 test('reuses existing Auth instance', () => {
   const auth1 = FirebaseStub.auth();
@@ -9,32 +9,6 @@ test('reuses existing Auth instance', () => {
   expect(auth1.uuid).toEqual(auth2.uuid);
 });
 
-test('returns anonymous user 1 when signing in anonymously', async () => {
-  const user = await FirebaseStub.auth().signInAnonymously();
-
-  expect(user).toBeTruthy();
-  expect(user.uid).toEqual(AuthConstants.anonymousUser1.uid);
-});
-
-test('calls onAuthStateChanged observer with anonymous user 1 when signing in anonymously', async () => {
-  let user = null;
-  let error = null;
-  FirebaseStub.auth().onAuthStateChanged(
-    (_user) => {
-      user = _user;
-    },
-    (_error) => {
-      error = _error;
-    },
-  );
-
-  await FirebaseStub.auth().signInAnonymously();
-
-  expect(user).toBeTruthy();
-  expect(user.uid).toEqual(AuthConstants.anonymousUser1.uid);
-  expect(error).toBeNull();
-});
-
 test('onAuthStateChanged unsubscribe removes observer', () => {
   const observer = () => {};
   const unsubscribe = FirebaseStub.auth().onAuthStateChanged(observer);
@@ -49,3 +23,13 @@ test('onAuthStateChanged unsubscribe removes observer', () => {
     FirebaseStub.auth().onAuthStateChangedObservers.indexOf(observer),
   ).not.toBeGreaterThanOrEqual(0);
 });
+
+test('current user delete calls signOut', async () => {
+  const mockSignOut = jest.spyOn(FirebaseStub.auth(), 'signOut');
+  await FirebaseStub.auth().signInAnonymously();
+  const { currentUser } = FirebaseStub.auth();
+
+  await currentUser.delete();
+
+  expect(mockSignOut).toHaveBeenCalledTimes(1);
+});
diff --git a/__mocks__/gatsby-plugin-firebase/auth/auth.js b/__mocks__/gatsby-plugin-firebase/auth/auth.js
index b8217a01..b0c123ea 100644
--- a/__mocks__/gatsby-plugin-firebase/auth/auth.js
+++ b/__mocks__/gatsby-plugin-firebase/auth/auth.js
@@ -60,7 +60,7 @@ class Auth {
       user.providerId,
       user.uid,
       user.isAnonymous,
-      this.signOut,
+      this.signOut.bind(this),
     );
 
     await delay(Constants.defaultDelayInMilliseconds);
@@ -98,7 +98,7 @@ class Auth {
       user.providerId,
       user.uid,
       user.isAnonymous,
-      this.signOut,
+      this.signOut.bind(this),
     );
 
     await delay(Constants.defaultDelayInMilliseconds);