diff --git a/static_src/reducers/userV0.test.js b/static_src/reducers/userV0.test.js
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+++ b/static_src/reducers/userV0.test.js
@@ -0,0 +1,372 @@
+// Copyright 2019 The Chromium Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+import {assert} from 'chai';
+import sinon from 'sinon';
+import * as userV0 from './userV0.js';
+import {prpcClient} from 'prpc-client-instance.js';
+
+
+let dispatch;
+
+describe('userV0', () => {
+  describe('reducers', () => {
+    it('SET_PREFS_SUCCESS updates existing prefs with new prefs', () => {
+      const state = {prefs: {
+        testPref: 'true',
+        anotherPref: 'hello-world',
+      }};
+
+      const newPrefs = [
+        {name: 'anotherPref', value: 'override'},
+        {name: 'newPref', value: 'test-me'},
+      ];
+
+      const newState = userV0.currentUserReducer(state,
+          {type: userV0.SET_PREFS_SUCCESS, newPrefs});
+
+      assert.deepEqual(newState, {prefs: {
+        testPref: 'true',
+        anotherPref: 'override',
+        newPref: 'test-me',
+      }});
+    });
+
+    it('FETCH_PROJECTS_SUCCESS overrides existing entry in usersById', () => {
+      const state = {
+        ['123']: {
+          projects: {
+            ownerOf: [],
+            memberOf: [],
+            contributorTo: [],
+            starredProjects: [],
+          },
+        },
+      };
+
+      const usersProjects = [
+        {
+          userRef: {userId: '123'},
+          ownerOf: ['chromium'],
+        },
+      ];
+
+      const newState = userV0.usersByIdReducer(state,
+          {type: userV0.FETCH_PROJECTS_SUCCESS, usersProjects});
+
+      assert.deepEqual(newState, {
+        ['123']: {
+          projects: {
+            ownerOf: ['chromium'],
+            memberOf: [],
+            contributorTo: [],
+            starredProjects: [],
+          },
+        },
+      });
+    });
+
+    it('FETCH_PROJECTS_SUCCESS adds new entry to usersById', () => {
+      const state = {
+        ['123']: {
+          projects: {
+            ownerOf: [],
+            memberOf: [],
+            contributorTo: [],
+            starredProjects: [],
+          },
+        },
+      };
+
+      const usersProjects = [
+        {
+          userRef: {userId: '543'},
+          ownerOf: ['chromium'],
+        },
+        {
+          userRef: {userId: '789'},
+          memberOf: ['v8'],
+        },
+      ];
+
+      const newState = userV0.usersByIdReducer(state,
+          {type: userV0.FETCH_PROJECTS_SUCCESS, usersProjects});
+
+      assert.deepEqual(newState, {
+        ['123']: {
+          projects: {
+            ownerOf: [],
+            memberOf: [],
+            contributorTo: [],
+            starredProjects: [],
+          },
+        },
+        ['543']: {
+          projects: {
+            ownerOf: ['chromium'],
+            memberOf: [],
+            contributorTo: [],
+            starredProjects: [],
+          },
+        },
+        ['789']: {
+          projects: {
+            ownerOf: [],
+            memberOf: ['v8'],
+            contributorTo: [],
+            starredProjects: [],
+          },
+        },
+      });
+    });
+
+    describe('GAPI_LOGIN_SUCCESS', () => {
+      it('sets currentUser.gapiEmail', () => {
+        const newState = userV0.currentUserReducer({}, {
+          type: userV0.GAPI_LOGIN_SUCCESS,
+          email: 'rutabaga@rutabaga.com',
+        });
+        assert.deepEqual(newState, {
+          gapiEmail: 'rutabaga@rutabaga.com',
+        });
+      });
+
+      it('defaults to an empty string', () => {
+        const newState = userV0.currentUserReducer({}, {
+          type: userV0.GAPI_LOGIN_SUCCESS,
+        });
+        assert.deepEqual(newState, {
+          gapiEmail: '',
+        });
+      });
+    });
+
+    describe('GAPI_LOGOUT_SUCCESS', () => {
+      it('sets currentUser.gapiEmail', () => {
+        const newState = userV0.currentUserReducer({}, {
+          type: userV0.GAPI_LOGOUT_SUCCESS,
+          email: '',
+        });
+        assert.deepEqual(newState, {
+          gapiEmail: '',
+        });
+      });
+
+      it('defaults to an empty string', () => {
+        const state = {};
+        const newState = userV0.currentUserReducer(state, {
+          type: userV0.GAPI_LOGOUT_SUCCESS,
+        });
+        assert.deepEqual(newState, {
+          gapiEmail: '',
+        });
+      });
+    });
+  });
+
+  describe('selectors', () => {
+    it('prefs', () => {
+      const state = wrapCurrentUser({prefs: {
+        testPref: 'true',
+        test_non_bool: 'hello-world',
+      }});
+
+      assert.deepEqual(userV0.prefs(state), new Map([
+        ['render_markdown', false],
+        ['testPref', true],
+        ['test_non_bool', 'hello-world'],
+      ]));
+    });
+
+    it('prefs is set with the correct type', async () =>{
+      // When setting prefs it's important that they are set as their
+      // String value.
+      const state = wrapCurrentUser({prefs: {
+        render_markdown : 'true',
+      }});
+      const markdownPref = userV0.prefs(state).get('render_markdown');
+      assert.isTrue(markdownPref);
+    });
+
+    it('prefs is NOT set with the correct type', async () =>{
+      // Here the value is a boolean so when it gets set it would
+      // appear as false because it's compared with a String.
+      const state = wrapCurrentUser({prefs: {
+        render_markdown : true,
+      }});
+      const markdownPref = userV0.prefs(state).get('render_markdown');
+      // Thus this is false when it was meant to be true.
+      assert.isFalse(markdownPref);
+    });
+
+    it('projects', () => {
+      assert.deepEqual(userV0.projects(wrapUser({})), {});
+
+      const state = wrapUser({
+        currentUser: {userId: '123'},
+        usersById: {
+          ['123']: {
+            projects: {
+              ownerOf: ['chromium'],
+              memberOf: ['v8'],
+              contributorTo: [],
+              starredProjects: [],
+            },
+          },
+        },
+      });
+
+      assert.deepEqual(userV0.projects(state), {
+        ownerOf: ['chromium'],
+        memberOf: ['v8'],
+        contributorTo: [],
+        starredProjects: [],
+      });
+    });
+
+    it('projectPerUser', () => {
+      assert.deepEqual(userV0.projectsPerUser(wrapUser({})), new Map());
+
+      const state = wrapUser({
+        usersById: {
+          ['123']: {
+            projects: {
+              ownerOf: ['chromium'],
+              memberOf: ['v8'],
+              contributorTo: [],
+              starredProjects: [],
+            },
+          },
+        },
+      });
+
+      assert.deepEqual(userV0.projectsPerUser(state), new Map([
+        ['123', {
+          ownerOf: ['chromium'],
+          memberOf: ['v8'],
+          contributorTo: [],
+          starredProjects: [],
+        }],
+      ]));
+    });
+  });
+
+  describe('action creators', () => {
+    beforeEach(() => {
+      sinon.stub(prpcClient, 'call');
+
+      dispatch = sinon.stub();
+    });
+
+    afterEach(() => {
+      prpcClient.call.restore();
+    });
+
+    it('fetchProjects succeeds', async () => {
+      const action = userV0.fetchProjects([{userId: '123'}]);
+
+      prpcClient.call.returns(Promise.resolve({
+        usersProjects: [
+          {
+            userRef: {
+              userId: '123',
+            },
+            ownerOf: ['chromium'],
+          },
+        ],
+      }));
+
+      await action(dispatch);
+
+      sinon.assert.calledWith(dispatch, {type: userV0.FETCH_PROJECTS_START});
+
+      sinon.assert.calledWith(
+          prpcClient.call,
+          'monorail.Users',
+          'GetUsersProjects',
+          {userRefs: [{userId: '123'}]});
+
+      sinon.assert.calledWith(dispatch, {
+        type: userV0.FETCH_PROJECTS_SUCCESS,
+        usersProjects: [
+          {
+            userRef: {
+              userId: '123',
+            },
+            ownerOf: ['chromium'],
+          },
+        ],
+      });
+    });
+
+    it('fetchProjects fails', async () => {
+      const action = userV0.fetchProjects([{userId: '123'}]);
+
+      const error = new Error('mistakes were made');
+      prpcClient.call.returns(Promise.reject(error));
+
+      await action(dispatch);
+
+      sinon.assert.calledWith(dispatch, {type: userV0.FETCH_PROJECTS_START});
+
+      sinon.assert.calledWith(
+          prpcClient.call,
+          'monorail.Users',
+          'GetUsersProjects',
+          {userRefs: [{userId: '123'}]});
+
+      sinon.assert.calledWith(dispatch, {
+        type: userV0.FETCH_PROJECTS_FAILURE,
+        error,
+      });
+    });
+
+    it('setPrefs', async () => {
+      const action = userV0.setPrefs([{name: 'pref_name', value: 'true'}]);
+
+      prpcClient.call.returns(Promise.resolve({}));
+
+      await action(dispatch);
+
+      sinon.assert.calledWith(dispatch, {type: userV0.SET_PREFS_START});
+
+      sinon.assert.calledWith(
+          prpcClient.call,
+          'monorail.Users',
+          'SetUserPrefs',
+          {prefs: [{name: 'pref_name', value: 'true'}]});
+
+      sinon.assert.calledWith(dispatch, {
+        type: userV0.SET_PREFS_SUCCESS,
+        newPrefs: [{name: 'pref_name', value: 'true'}],
+      });
+    });
+
+    it('setPrefs fails', async () => {
+      const action = userV0.setPrefs([{name: 'pref_name', value: 'true'}]);
+
+      const error = new Error('mistakes were made');
+      prpcClient.call.returns(Promise.reject(error));
+
+      await action(dispatch);
+
+      sinon.assert.calledWith(dispatch, {type: userV0.SET_PREFS_START});
+
+      sinon.assert.calledWith(
+          prpcClient.call,
+          'monorail.Users',
+          'SetUserPrefs',
+          {prefs: [{name: 'pref_name', value: 'true'}]});
+
+      sinon.assert.calledWith(dispatch, {
+        type: userV0.SET_PREFS_FAILURE,
+        error,
+      });
+    });
+  });
+});
+
+
+const wrapCurrentUser = (currentUser = {}) => ({userV0: {currentUser}});
+const wrapUser = (user) => ({userV0: user});