diff --git a/library/Businessprocess/BusinessProcess.php b/library/Businessprocess/BusinessProcess.php
index 88989c2..c852e83 100644
--- a/library/Businessprocess/BusinessProcess.php
+++ b/library/Businessprocess/BusinessProcess.php
@@ -524,6 +524,20 @@ class BusinessProcess
         );
     }
 
+    /**
+     * Set the state for a specific node
+     *
+     * @param string $name  Node name
+     * @param int    $state Desired state
+     *
+     * @return $this
+     */
+    public function setNodeState($name, $state)
+    {
+        $this->getNode($name)->setState($state);
+        return $this;
+    }
+
     public function addObjectName($name)
     {
         $this->all_checks[$name] = 1;
diff --git a/test/php/library/Businessprocess/Operators/AndOperatorTest.php b/test/php/library/Businessprocess/Operators/AndOperatorTest.php
new file mode 100644
index 0000000..fbd3791
--- /dev/null
+++ b/test/php/library/Businessprocess/Operators/AndOperatorTest.php
@@ -0,0 +1,119 @@
+<?php
+
+namespace Tests\Icinga\Module\Businessprocess\Operator;
+
+use Icinga\Module\Businessprocess\BusinessProcess;
+use Icinga\Module\Businessprocess\Test\BaseTestCase;
+use Icinga\Module\Businessprocess\Storage\LegacyStorage;
+
+class AndOperatorTest extends BaseTestCase
+{
+    public function testTheOperatorCanBeParsed()
+    {
+        $storage = new LegacyStorage($this->emptyConfigSection());
+        $expressions = array(
+            'a = b',
+            'a = b & c & d',
+        );
+
+        foreach ($expressions as $expression) {
+            $this->assertInstanceOf(
+                'Icinga\\Module\\Businessprocess\\Businessprocess',
+                $storage->loadFromString('dummy', $expression)
+            );
+        }
+    }
+
+    public function testThreeTimesCriticalIsCritical()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 2);
+        $bp->setNodeState('d', 2);
+
+        $this->assertEquals(
+            'CRITICAL',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoTimesCriticalAndOkIsCritical()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 0);
+        $bp->setNodeState('d', 2);
+
+        $this->assertEquals(
+            'CRITICAL',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testCriticalAndWarningAndOkIsCritical()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 0);
+
+        $this->assertEquals(
+            'CRITICAL',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testUnknownAndWarningAndOkIsUnknown()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 0);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 3);
+
+        $this->assertEquals(
+            'UNKNOWN',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoTimesWarningAndOkIsWarning()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 0);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 1);
+
+        $this->assertEquals(
+            'WARNING',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testThreeTimesOkIsOk()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 0);
+        $bp->setNodeState('c', 0);
+        $bp->setNodeState('d', 0);
+
+        $this->assertEquals(
+            'OK',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    /**
+     * @return BusinessProcess
+     */
+    protected function getBp()
+    {
+        $storage = new LegacyStorage($this->emptyConfigSection());
+        $expression = 'a = b & c & d';
+        $bp = $storage->loadFromString('dummy', $expression);
+        $bp->createBp('b');
+        $bp->createBp('c');
+        $bp->createBp('d');
+
+        return $bp;
+    }
+}
diff --git a/test/php/library/Businessprocess/Operators/MinOperatorTest.php b/test/php/library/Businessprocess/Operators/MinOperatorTest.php
new file mode 100644
index 0000000..43126dd
--- /dev/null
+++ b/test/php/library/Businessprocess/Operators/MinOperatorTest.php
@@ -0,0 +1,118 @@
+<?php
+
+namespace Tests\Icinga\Module\Businessprocess\Operator;
+
+use Icinga\Module\Businessprocess\BusinessProcess;
+use Icinga\Module\Businessprocess\Test\BaseTestCase;
+use Icinga\Module\Businessprocess\Storage\LegacyStorage;
+
+class MinOperatorTest extends BaseTestCase
+{
+    public function testTheOperatorCanBeParsed()
+    {
+        $storage = new LegacyStorage($this->emptyConfigSection());
+        $expressions = array(
+            'a = 1 of: b',
+            'a = 2 of: b + c + d',
+        );
+        $this->getName();
+        foreach ($expressions as $expression) {
+            $this->assertInstanceOf(
+                'Icinga\\Module\\Businessprocess\\Businessprocess',
+                $storage->loadFromString('dummy', $expression)
+            );
+        }
+    }
+    public function testTwoOfThreeTimesCriticalAreAtLeastCritical()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 2);
+        $bp->setNodeState('d', 2);
+
+        $this->assertEquals(
+            'CRITICAL',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoOfTwoTimesCriticalAndUnknownAreAtLeastCritical()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 3);
+        $bp->setNodeState('d', 2);
+
+        $this->assertEquals(
+            'CRITICAL',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoOfCriticalAndWarningAndOkAreAtLeastWarning()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 0);
+
+        $this->assertEquals(
+            'WARNING',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoOfUnknownAndWarningAndCriticalAreAtLeastUnknown()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 3);
+
+        $this->assertEquals(
+            'UNKNOWN',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoOfTwoTimesWarningAndUnknownAreAtLeastWarning()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 0);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 1);
+
+        $this->assertEquals(
+            'WARNING',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoOfThreeTimesOkAreAtLeastOk()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 0);
+        $bp->setNodeState('c', 0);
+        $bp->setNodeState('d', 0);
+
+        $this->assertEquals(
+            'OK',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    /**
+     * @return BusinessProcess
+     */
+    protected function getBp()
+    {
+        $storage = new LegacyStorage($this->emptyConfigSection());
+        $expression = 'a = 2 of: b + c + d';
+        $bp = $storage->loadFromString('dummy', $expression);
+        $bp->createBp('b');
+        $bp->createBp('c');
+        $bp->createBp('d');
+
+        return $bp;
+    }
+}
diff --git a/test/php/library/Businessprocess/Operators/OrOperatorTest.php b/test/php/library/Businessprocess/Operators/OrOperatorTest.php
new file mode 100644
index 0000000..ac2f5f3
--- /dev/null
+++ b/test/php/library/Businessprocess/Operators/OrOperatorTest.php
@@ -0,0 +1,119 @@
+<?php
+
+namespace Tests\Icinga\Module\Businessprocess\Operator;
+
+use Icinga\Module\Businessprocess\BusinessProcess;
+use Icinga\Module\Businessprocess\Test\BaseTestCase;
+use Icinga\Module\Businessprocess\Storage\LegacyStorage;
+
+class OrOperatorTest extends BaseTestCase
+{
+    public function testTheOperatorCanBeParsed()
+    {
+        $storage = new LegacyStorage($this->emptyConfigSection());
+        $expressions = array(
+            'a = b',
+            'a = b | c | d',
+        );
+
+        foreach ($expressions as $expression) {
+            $this->assertInstanceOf(
+                'Icinga\\Module\\Businessprocess\\Businessprocess',
+                $storage->loadFromString('dummy', $expression)
+            );
+        }
+    }
+
+    public function testThreeTimesCriticalIsCritical()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 2);
+        $bp->setNodeState('d', 2);
+
+        $this->assertEquals(
+            'CRITICAL',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoTimesCriticalOrUnknownIsUnknown()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 3);
+        $bp->setNodeState('d', 2);
+
+        $this->assertEquals(
+            'UNKNOWN',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testCriticalOrWarningOrOkIsOk()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 0);
+
+        $this->assertEquals(
+            'OK',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testUnknownOrWarningOrCriticalIsWarning()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 2);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 3);
+
+        $this->assertEquals(
+            'WARNING',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testTwoTimesWarningAndOkIsOk()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 0);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 1);
+
+        $this->assertEquals(
+            'OK',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    public function testThreeTimesWarningIsWarning()
+    {
+        $bp = $this->getBp();
+        $bp->setNodeState('b', 1);
+        $bp->setNodeState('c', 1);
+        $bp->setNodeState('d', 1);
+
+        $this->assertEquals(
+            'WARNING',
+            $bp->getNode('a')->getStateName()
+        );
+    }
+
+    /**
+     * @return BusinessProcess
+     */
+    protected function getBp()
+    {
+        $storage = new LegacyStorage($this->emptyConfigSection());
+        $expression = 'a = b | c | d';
+        $bp = $storage->loadFromString('dummy', $expression);
+        $bp->createBp('b');
+        $bp->createBp('c');
+        $bp->createBp('d');
+
+        return $bp;
+    }
+}