Don't truncate lockfiles, fix tests

src/BenConstable/Lock/Lock.php

@@ -64,7 +64,7 @@ public function __destruct()
     public function acquire()
     {
         if (!$this->locked) {
-            $this->fp = @fopen($this->filePath, 'w');
+            $this->fp = @fopen($this->filePath, 'a');
 
             if (!$this->fp || !flock($this->fp, LOCK_EX | LOCK_NB)) {
                 throw new LockException("Could not get lock on {$this->filePath}");

tests/spec/BenConstable/Lock/LockSpec.php

@@ -27,6 +27,18 @@ function it_acquires_a_lock_on_an_existing_file()
         $this->release();
     }
 
+    function it_acquires_a_lock_on_a_non_existing_file()
+    {
+        $this->beConstructedWith($this->lockTestPath . '/test-lock-not-exists.txt');
+
+        $this->acquire()
+            ->shouldBe($this);
+
+        $this->release();
+
+        unlink($this->lockTestPath . '/test-lock-not-exists.txt');
+    }
+
     function it_returns_the_same_lock_when_locking_more_than_once()
     {
         $this->beConstructedWith($this->lockTestPath . '/test-lock.txt');
@@ -52,15 +64,6 @@ function it_fails_to_aquire_a_lock_on_an_already_locked_file()
             ->during('acquire');
     }
 
-    function it_fails_to_acquire_a_lock_on_a_non_existing_file()
-    {
-        $this->beConstructedWith($this->lockTestPath . '/test-lock-not-exists.txt');
-
-        $this
-            ->shouldThrow('BenConstable\Lock\Exception\LockException')
-            ->during('acquire');
-    }
-
     function it_releases_a_lock_so_it_can_be_locked_by_something_else()
     {
         $this->beConstructedWith($this->lockTestPath . '/test-lock.txt');