diff --git a/tests/cases/User/TestUser.php b/tests/cases/User/TestUser.php
new file mode 100644
index 0000000..f5a746a
--- /dev/null
+++ b/tests/cases/User/TestUser.php
@@ -0,0 +1,225 @@
+<?php
+/** @license MIT
+ * Copyright 2017 J. King, Dustin Wilson et al.
+ * See LICENSE and AUTHORS files for details */
+
+declare(strict_types=1);
+namespace JKingWeb\Arsse\TestCase\User;
+
+use JKingWeb\Arsse\Arsse;
+use JKingWeb\Arsse\Conf;
+use JKingWeb\Arsse\Database;
+use JKingWeb\Arsse\User;
+use JKingWeb\Arsse\AbstractException as Exception;
+use JKingWeb\Arsse\User\Driver;
+use JKingWeb\Arsse\User\Internal\Driver as InternalDriver;
+use Phake;
+
+/** @covers \JKingWeb\Arsse\User */
+class TestUser extends \JKingWeb\Arsse\Test\AbstractTest {
+    public static function setUpBeforeClass() {
+        Arsse::$lang = new \JKingWeb\Arsse\Lang();
+    }
+
+    public function setUp() {
+        $this->clearData();
+        Arsse::$conf = new Conf;
+        // create a mock database interface
+        Arsse::$db = Phake::mock(Database::class);
+        Phake::when(Arsse::$db)->begin->thenReturn(Phake::mock(\JKingWeb\Arsse\Db\Transaction::class));
+    }
+
+    public function provideDriver() {
+        yield "Internal driver" => [Phake::mock(InternalDriver::class)];
+        yield "Non-Internal Driver" => [Phake::mock(Driver::class)];
+    }
+
+    /** @dataProvider provideDriver */
+    public function testConstruct(Driver $driver) {
+        $this->assertInstanceOf(User::class, new User($driver));
+    }
+
+    public function testConstructConfiguredDriver() {
+        $this->assertInstanceOf(User::class, new User);
+    }
+
+    public function testConversionToString() {
+        $u = new User;
+        $u->id = "john.doe@example.com";
+        $this->assertSame("john.doe@example.com", (string) $u);
+        $u->id = null;
+        $this->assertSame("", (string) $u);
+    }
+
+    /** @dataProvider provideAuthentication */
+    public function testAuthenticateAUser(Driver $driver, bool $preAuth, string $user, string $password, bool $exp) {
+        Arsse::$conf->userPreAuth = $preAuth;
+        Phake::when($driver)->auth->thenReturn(false);
+        Phake::when($driver)->auth("john.doe@example.com", "secret")->thenReturn(true);
+        Phake::when($driver)->auth("jane.doe@example.com", "superman")->thenReturn(true);
+        Phake::when(Arsse::$db)->userExists("john.doe@example.com")->thenReturn(true);
+        Phake::when(Arsse::$db)->userExists("jane.doe@example.com")->thenReturn(false);
+        Phake::when(Arsse::$db)->userAdd->thenReturn("");
+        $u = new User($driver);
+        $this->assertSame($exp, $u->auth($user, $password));
+        $this->assertNull($u->id);
+        Phake::verify(Arsse::$db, Phake::times($exp ? 1 : 0))->userExists($user);
+        Phake::verify(Arsse::$db, Phake::times($exp && $user == "jane.doe@example.com" ? 1 : 0))->userAdd($user, $password);
+    }
+
+    public function provideAuthentication() {
+        $john = "john.doe@example.com";
+        $jane = "jane.doe@example.com";
+        $tests = [
+            [false, $john, "secret",   true],
+            [false, $john, "superman", false],
+            [false, $jane, "secret",   false],
+            [false, $jane, "superman", true],
+            [true,  $john, "secret",   true],
+            [true,  $john, "superman", true],
+            [true,  $jane, "secret",   true],
+            [true,  $jane, "superman", true],
+        ];
+        for ($a = 0; $a < sizeof($tests); $a++) {
+            list($preAuth, $user, $password, $outcome) = $tests[$a];
+            foreach ($this->provideDriver() as $name => list($driver)) {
+                yield "$name #$a" => [$driver, $preAuth, $user, $password, $outcome];
+            }
+        }
+    }
+
+    /** @dataProvider provideUserList */
+    public function testListUsers(Driver $driver, bool $authorized, $exp) {
+        $u = new User($driver);
+        Phake::when($driver)->authorize->thenReturn($authorized);
+        Phake::when($driver)->userList->thenReturn(["john.doe@example.com", "jane.doe@example.com"]);
+        if ($exp instanceof Exception) {
+            $this->assertException("notAuthorized", "User", "ExceptionAuthz");
+        }
+        $this->assertSame($exp, $u->list());
+    }
+
+    public function provideUserList() {
+        $john = "john.doe@example.com";
+        $jane = "jane.doe@example.com";
+        $tests = [
+            [false, new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [true,  [$john, $jane]],
+        ];
+        for ($a = 0; $a < sizeof($tests); $a++) {
+            list($authorized, $outcome) = $tests[$a];
+            foreach ($this->provideDriver() as $name => list($driver)) {
+                yield "$name #$a" => [$driver, $authorized, $outcome];
+            }
+        }
+    }
+
+    /** @dataProvider provideExistence */
+    public function testCheckThatAUserExists(Driver $driver, bool $authorized, string $user, $exp) {
+        $u = new User($driver);
+        Phake::when($driver)->authorize->thenReturn($authorized);
+        Phake::when($driver)->userExists("john.doe@example.com")->thenReturn(true);
+        Phake::when($driver)->userExists("jane.doe@example.com")->thenReturn(false);
+        if ($exp instanceof Exception) {
+            $this->assertException("notAuthorized", "User", "ExceptionAuthz");
+        }
+        $this->assertSame($exp, $u->exists($user));
+    }
+
+    public function provideExistence() {
+        $john = "john.doe@example.com";
+        $jane = "jane.doe@example.com";
+        $tests = [
+            [false, $john, new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [false, $jane, new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [true,  $john, true],
+            [true,  $jane, false],
+        ];
+        for ($a = 0; $a < sizeof($tests); $a++) {
+            list($authorized, $user, $outcome) = $tests[$a];
+            foreach ($this->provideDriver() as $name => list($driver)) {
+                yield "$name #$a" => [$driver, $authorized, $user, $outcome];
+            }
+        }
+    }
+
+    /** @dataProvider provideAdditions */
+    public function testAddAUser(Driver $driver, bool $authorized, string $user, $password, $exp) {
+        $u = new User($driver);
+        Phake::when($driver)->authorize->thenReturn($authorized);
+        Phake::when($driver)->userAdd("john.doe@example.com", $this->anything())->thenThrow(new \JKingWeb\Arsse\User\Exception("alreadyExists"));
+        Phake::when($driver)->userAdd("jane.doe@example.com", $this->anything())->thenReturnCallback(function($user, $pass) {
+            return $pass ?? "random password";
+        });
+        if ($exp instanceof Exception) {
+            if ($exp instanceof \JKingWeb\Arsse\User\ExceptionAuthz) {
+                $this->assertException("notAuthorized", "User", "ExceptionAuthz");
+            } else {
+                $this->assertException("alreadyExists", "User");
+            }
+        }
+        $this->assertSame($exp, $u->add($user, $password));
+    }
+
+    public function provideAdditions() {
+        $john = "john.doe@example.com";
+        $jane = "jane.doe@example.com";
+        $tests = [
+            [false, $john, "secret",   new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [false, $jane, "superman", new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [true,  $john, "secret",   new \JKingWeb\Arsse\User\Exception("alreadyExists")],
+            [true,  $jane, "superman", "superman"],
+            [true,  $jane, null,       "random password"],
+        ];
+        for ($a = 0; $a < sizeof($tests); $a++) {
+            list($authorized, $user, $password, $outcome) = $tests[$a];
+            foreach ($this->provideDriver() as $name => list($driver)) {
+                yield "$name #$a" => [$driver, $authorized, $user, $password, $outcome];
+            }
+        }
+    }
+
+    /** @dataProvider provideRemovals */
+    public function testRemoveAUser(Driver $driver, bool $authorized, string $user, bool $exists, $exp) {
+        $u = new User($driver);
+        Phake::when($driver)->authorize->thenReturn($authorized);
+        Phake::when($driver)->userRemove("john.doe@example.com")->thenReturn(true);
+        Phake::when($driver)->userRemove("jane.doe@example.com")->thenThrow(new \JKingWeb\Arsse\User\Exception("doesNotExist"));
+        Phake::when(Arsse::$db)->userExists->thenReturn($exists);
+        Phake::when(Arsse::$db)->userRemove->thenReturn(true);
+        if ($exp instanceof Exception) {
+            if ($exp instanceof \JKingWeb\Arsse\User\ExceptionAuthz) {
+                $this->assertException("notAuthorized", "User", "ExceptionAuthz");
+            } else {
+                $this->assertException("doesNotExist", "User");
+            }
+        }
+        try {
+            $this->assertSame($exp, $u->remove($user));
+        } finally {
+            Phake::verify(Arsse::$db, Phake::times((int) $authorized))->userExists($user);
+            Phake::verify(Arsse::$db, Phake::times((int) ($authorized && $exists)))->userRemove($user);
+        }
+    }
+
+    public function provideRemovals() {
+        $john = "john.doe@example.com";
+        $jane = "jane.doe@example.com";
+        $tests = [
+            [false, $john, true,  new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [false, $john, false, new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [false, $jane, true,  new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [false, $jane, false, new \JKingWeb\Arsse\User\ExceptionAuthz("notAuthorized")],
+            [true,  $john, true,  true],
+            [true,  $john, false, true],
+            [true,  $jane, true,  new \JKingWeb\Arsse\User\Exception("doesNotExist")],
+            [true,  $jane, false, new \JKingWeb\Arsse\User\Exception("doesNotExist")],
+        ];
+        for ($a = 0; $a < sizeof($tests); $a++) {
+            list($authorized, $user, $exists, $outcome) = $tests[$a];
+            foreach ($this->provideDriver() as $name => list($driver)) {
+                yield "$name #$a" => [$driver, $authorized, $user, $exists, $outcome];
+            }
+        }
+    }
+}