diff --git a/system/Common.php b/system/Common.php
index 48bb5bddbe..61380b9ff7 100644
--- a/system/Common.php
+++ b/system/Common.php
@@ -440,8 +440,10 @@ if ( ! function_exists('log_message'))
 			return $logger->log($level, $message, $context);
 		}
 
+		// @codeCoverageIgnoreStart
 		return Services::logger(true)
 						->log($level, $message, $context);
+		// @codeCoverageIgnoreEnd
 	}
 
 }
@@ -668,6 +670,9 @@ if ( ! function_exists('force_https'))
 	 *                                    Defaults to 1 year.
 	 * @param RequestInterface  $request
 	 * @param ResponseInterface $response
+	 * 
+	 * Not testable, as it will exit!
+	 * @codeCoverageIgnore
 	 */
 	function force_https(int $duration = 31536000, RequestInterface $request = null, ResponseInterface $response = null)
 	{
@@ -837,6 +842,8 @@ if ( ! function_exists('is_really_writable'))
 	 * @param   string $file
 	 *
 	 * @return  bool
+	 * 
+	 * @codeCoverageIgnore	Not practical to test, as travis runs on linux
 	 */
 	function is_really_writable($file)
 	{
@@ -931,6 +938,8 @@ if ( ! function_exists('function_usable'))
 	 * @param	string	$function_name	Function to check for
 	 * @return	bool	TRUE if the function exists and is safe to call,
 	 * 			FALSE otherwise.
+	 * 
+	 * @codeCoverageIgnore	This is too exotic
 	 */
 	function function_usable($function_name)
 	{
@@ -959,6 +968,8 @@ if (! function_exists('dd'))
 	 * Prints a Kint debug report and exits.
 	 *
 	 * @param array ...$vars
+	 * 
+	 * @codeCoverageIgnore	Can't be tested ... exits
 	 */
 	function dd(...$vars)
 	{
diff --git a/tests/_support/View/Views/simple.php b/tests/_support/View/Views/simple.php
new file mode 100644
index 0000000000..afd6c25fe2
--- /dev/null
+++ b/tests/_support/View/Views/simple.php
@@ -0,0 +1 @@
+<h1><?= $testString ?></h1>
\ No newline at end of file
diff --git a/tests/system/CommonFunctionsTest.php b/tests/system/CommonFunctionsTest.php
index e5ac5b327c..0c88d29c25 100644
--- a/tests/system/CommonFunctionsTest.php
+++ b/tests/system/CommonFunctionsTest.php
@@ -1,5 +1,16 @@
 <?php
 
+use Config\App;
+use Config\Autoload;
+use CodeIgniter\Config\Services;
+use CodeIgniter\Router\RouteCollection;
+use CodeIgniter\HTTP\RequestResponse;
+use CodeIgniter\HTTP\RedirectResponse;
+use CodeIgniter\HTTP\URI;
+use CodeIgniter\HTTP\UserAgent;
+use Tests\Support\Autoloader\MockFileLocator;
+use Tests\Support\HTTP\MockIncomingRequest;
+
 /**
  * @backupGlobals enabled
  */
@@ -12,7 +23,7 @@ class CommomFunctionsTest extends \CIUnitTestCase
 	{
 		parent::setUp();
 
-	    unset($_ENV['foo'], $_SERVER['foo']);
+		unset($_ENV['foo'], $_SERVER['foo']);
 	}
 
 	//--------------------------------------------------------------------
@@ -48,40 +59,220 @@ class CommomFunctionsTest extends \CIUnitTestCase
 
 	// ------------------------------------------------------------------------
 
-    public function testEnvReturnsDefault()
-    {
-        $this->assertEquals('baz', env('foo', 'baz'));
-    }
+	public function testEnvReturnsDefault()
+	{
+		$this->assertEquals('baz', env('foo', 'baz'));
+	}
 
-    public function testEnvGetsFromSERVER()
-    {
-        $_SERVER['foo'] = 'bar';
+	public function testEnvGetsFromSERVER()
+	{
+		$_SERVER['foo'] = 'bar';
 
-        $this->assertEquals('bar', env('foo', 'baz'));
-    }
+		$this->assertEquals('bar', env('foo', 'baz'));
+	}
 
-    public function testEnvGetsFromENV()
-    {
-        $_ENV['foo'] = 'bar';
+	public function testEnvGetsFromENV()
+	{
+		$_ENV['foo'] = 'bar';
 
-        $this->assertEquals('bar', env('foo', 'baz'));
-    }
+		$this->assertEquals('bar', env('foo', 'baz'));
+	}
+
+	public function testEnvBooleans()
+	{
+		$_ENV['p1'] = 'true';
+		$_ENV['p2'] = 'false';
+		$_ENV['p3'] = 'empty';
+		$_ENV['p4'] = 'null';
+
+		$this->assertTrue(env('p1'));
+		$this->assertFalse(env('p2'));
+		$this->assertEmpty(env('p3'));
+		$this->assertNull(env('p4'));
+	}
+
+	// ------------------------------------------------------------------------
 
 	public function testRedirectReturnsRedirectResponse()
 	{
 		$_SERVER['REQUEST_METHOD'] = 'GET';
 
 		$response = $this->createMock(\CodeIgniter\HTTP\Response::class);
-		$routes   = new \CodeIgniter\Router\RouteCollection(new \Tests\Support\Autoloader\MockFileLocator(new \Config\Autoload()));
+		$routes = new \CodeIgniter\Router\RouteCollection(new \Tests\Support\Autoloader\MockFileLocator(new \Config\Autoload()));
 		\CodeIgniter\Services::injectMock('response', $response);
 		\CodeIgniter\Services::injectMock('routes', $routes);
 
 		$routes->add('home/base', 'Controller::index', ['as' => 'base']);
 
 		$response->method('redirect')
-			->will($this->returnArgument(0));
+				->will($this->returnArgument(0));
 
 		$this->assertInstanceOf(\CodeIgniter\HTTP\RedirectResponse::class, redirect('base'));
-    }
+	}
+
+	public function testRedirectDefault()
+	{
+		$this->assertInstanceOf(\CodeIgniter\HTTP\RedirectResponse::class, redirect());
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testView()
+	{
+		$data = [
+			'testString' => 'bar',
+			'bar'		 => 'baz',
+		];
+		$expected = '<h1>bar</h1>';
+		$this->assertContains($expected, view('\Tests\Support\View\Views\simple', $data, []));
+	}
+
+	public function testViewSavedData()
+	{
+		$data = [
+			'testString' => 'bar',
+			'bar'		 => 'baz',
+		];
+		$expected = '<h1>bar</h1>';
+		$this->assertContains($expected, view('\Tests\Support\View\Views\simple', $data, ['saveData' => true]));
+		$this->assertContains($expected, view('\Tests\Support\View\Views\simple'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testViewCell()
+	{
+		$expected = 'Hello';
+		$this->assertEquals($expected, view_cell('\CodeIgniter\View\SampleClass::hello'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testEscapeBadContext()
+	{
+		$this->expectException(InvalidArgumentException::class);
+		esc(['width' => '800', 'height' => '600'], 'bogus');
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testSessionInstance()
+	{
+		$this->assertInstanceOf(CodeIgniter\Session\Session::class, session());
+	}
+
+	public function testSessionVariable()
+	{
+		$_SESSION['notbogus'] = 'Hi there';
+		$this->assertEquals('Hi there', session('notbogus'));
+	}
+
+	public function testSessionVariableNotThere()
+	{
+		$_SESSION['bogus'] = 'Hi there';
+		$this->assertEquals(null, session('notbogus'));
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testSingleService()
+	{
+		$timer1 = single_service('timer');
+		$timer2 = single_service('timer');
+		$this->assertFalse($timer1 === $timer2);
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testRouteTo()
+	{
+		// prime the pump
+		$routes = service('routes');
+		$routes->add('path/(:any)/to/(:num)', 'myController::goto/$1/$2');
+
+		$this->assertEquals('/path/string/to/13', route_to('myController::goto', 'string', 13));
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testInvisible()
+	{
+		$this->assertEquals('Javascript', remove_invisible_characters("Java\0script"));
+	}
+
+	public function testInvisibleEncoded()
+	{
+		$this->assertEquals('Javascript', remove_invisible_characters("Java%0cscript", true));
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testAppTimezone()
+	{
+		$this->assertEquals('America/Chicago', app_timezone());
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testCSRFToken()
+	{
+		$this->assertEquals('csrf_test_name', csrf_token());
+	}
+
+	public function testHash()
+	{
+		$this->assertEquals(32, strlen(csrf_hash()));
+	}
+
+	public function testCSRFField()
+	{
+		$this->assertContains('<input type="hidden" ', csrf_field());
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testOldInput()
+	{
+		// setup from RedirectResponseTest...
+		$_SERVER['REQUEST_METHOD'] = 'GET';
+
+		$this->config = new App();
+		$this->config->baseURL = 'http://example.com';
+
+		$this->routes = new RouteCollection(new MockFileLocator(new Autoload()));
+		Services::injectMock('routes', $this->routes);
+
+		$this->request = new MockIncomingRequest($this->config, new URI('http://example.com'), null, new UserAgent());
+		Services::injectMock('request', $this->request);
+
+		// setup & ask for a redirect...
+		$_SESSION = [];
+		$_GET = ['foo' => 'bar'];
+		$_POST = ['bar' => 'baz', 'zibble' => serialize('fritz')];
+
+		$response = new RedirectResponse(new App());
+		$returned = $response->withInput();
+
+		$this->assertEquals('bar', old('foo')); // regular parameter
+		$this->assertEquals('doo', old('yabba dabba', 'doo')); // non-existing parameter
+		$this->assertEquals('fritz', old('zibble')); // serialized parameter
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testReallyWritable()
+	{
+		// cannot test fully on *nix
+		$this->assertTrue(is_really_writable(WRITEPATH));
+	}
+
+	// ------------------------------------------------------------------------
+
+	public function testSlashItem()
+	{
+		$this->assertEquals('/', slash_item('cookiePath')); // slash already there
+		$this->assertEquals('', slash_item('cookieDomain')); // empty, so untouched
+		$this->assertEquals('en/', slash_item('defaultLocale')); // slash appended
+	}
 
 }