If no ratings are common, dont recommend

phpunit.xml.dist

@@ -13,15 +13,16 @@
 >
     <testsuites>
         <testsuite name="Default">
-            <directory>./Tests/</directory>
+            <directory>./tests/</directory>
         </testsuite>
     </testsuites>
 
     <filter>
         <whitelist>
-            <directory>./</directory>
+            <directory>./src</directory>
             <exclude>
-                <directory>./Tests</directory>
+                <directory>./tests</directory>
+                <directory>./vendor</directory>
             </exclude>
         </whitelist>
     </filter>

src/stojg/datamine/Recommender.php

@@ -68,8 +68,14 @@ protected function findNearest($strategy)
                 continue;
             }
             $distance = $strategy->run($itemData, $this->set[$this->item]);
+            if($distance === false) {
+                continue;
+            }
             $distances[] = array('key' => $key, 'value' => $distance);
         }
+        if(!count($distances)) {
+            return false;
+        }
         $this->sort($distances, true);
         return $distances[0]['key'];
     }

src/stojg/datamine/strategy/Minkowski.php

@@ -49,6 +49,6 @@ public function run($rating1, $rating2)
         if ($commonRatings) {
             return pow($distance, 1 / $this->r);
         }
-        return 0;
+        return false;
     }
 }

tests/RecommenderTest.php

@@ -61,12 +61,20 @@ public function testRecommendPaersonHailey()
         $base = new Recommender('Hailey', $this->set);
         $recommendations = $base->recommend(new Paerson());
         $this->assertEquals(3, count($recommendations));
-        $this->assertEquals('Phoenix', $recommendations[0]['key']);
-        $this->assertEquals(4.0, $recommendations[0]['value']);
-        $this->assertEquals('Blues Traveler', $recommendations[1]['key']);
-        $this->assertEquals(3.0, $recommendations[1]['value']);
+        $this->assertEquals('Blues Traveler', $recommendations[0]['key']);
+        $this->assertEquals(5.0, $recommendations[0]['value']);
+        $this->assertEquals('Phoenix', $recommendations[1]['key']);
+        $this->assertEquals(5.0, $recommendations[1]['value']);
         $this->assertEquals('Slightly Stoopid', $recommendations[2]['key']);
-        $this->assertEquals(2.5, $recommendations[2]['value']);
+        $this->assertEquals(4.0, $recommendations[2]['value']);
+    }
+
+    public function testRecommendPaersonNoMatch()
+    {
+        $set = json_decode(file_get_contents(__DIR__ . '/fixtures/users_nomatch.json'), true);
+        $base = new Recommender('Andrea', $set);
+        $recommendations = $base->recommend(new Paerson());
+        $this->assertEquals(0, count($recommendations));
     }
 
     public function testRecommendCosineHailey()

tests/fixtures/users_nomatch.json

@@ -0,0 +1,14 @@
+{
+	"Andrea": {
+		"Blues Traveler": 1.0,
+		"Broken Bells": 2.0,
+		"Norah Jones": 3.0,
+		"The Strokes": 4.0
+	},
+	"Bob": {
+		"Deadmau5": 1.0,
+		"Phoenix": 2.0,
+		"Slightly Stoopid": 3.0,
+		"Vampire Weekend": 4.0
+	}
+}

tests/strategy/MinkowskiTest.php

@@ -21,4 +21,12 @@ public function testMinkowskiAngelicaHailey()
         $score = $paerson->run($this->set['Angelica'], $this->set['Hailey']);
         $this->assertEquals(2.7386127875258, $score);
     }
+
+    public function testMinkowskiNoMatch()
+    {
+        $set = json_decode(file_get_contents(__DIR__ . '/../fixtures/users_nomatch.json'), true);
+        $paerson = new Minkowski(2);
+        $score = $paerson->run($set['Andrea'], $set['Bob']);
+        $this->assertFalse($score);
+    }
 }