Allow absolute paths to be given.

Both bash and zsh support absolute paths being given to where, so it
only makes sense for this to as well.  When given the absolute path, the
configured paths are ignored and only the single absolute path is
considered.

src/Locator.php

@@ -90,6 +90,10 @@ public function locateAll($command)
      */
     protected function _getPotentialCommandLocations($command)
     {
+        if ($this->_isAbsoluteCommandPath($command)) {
+            return array($command);
+        }
+
         $getCommandPath = function($path) use($command) {
             return "{$path}/{$command}";
         };
@@ -108,13 +112,26 @@ protected function _getPaths()
     }
 
     /**
-     * Checks to see if the command (basename) is an allowed name for a command.
+     * Checks to see if the command is an allowed name for a command.
      *
      * @param string $command The command name to check.
      * @return bool The validity of the command name.
      */
     protected function _isValidCommandName($command)
     {
-        return strpos($command, '/') === false && $command !== '.' && $command !== '..';
+        $isSubdirectory = strpos($command, '/') !== false && !$this->_isAbsoluteCommandPath($command);
+        $isDotDirectory = $command === '.' || $command === '..';
+        return !$isSubdirectory && !$isDotDirectory;
+    }
+
+    /**
+     * Checks to see if the command is an absolute path.
+     *
+     * @param string $command The command name to check.
+     * @return bool True if the command is an absolute path, false otherwise.
+     */
+    protected function _isAbsoluteCommandPath($command)
+    {
+        return $command[0] === '/';
     }
 }

tests/LocatorTest.php

@@ -19,6 +19,7 @@ class LocatorTest extends PHPUnit_Framework_TestCase
      * @covers ::_getPotentialCommandLocations
      * @covers ::_getPaths
      * @covers ::_isValidCommandName
+     * @covers ::_isAbsoluteCommandPath
      */
     public function locateSimpleCommand()
     {
@@ -40,6 +41,7 @@ public function locateSimpleCommand()
      * @covers ::_getPotentialCommandLocations
      * @covers ::_getPaths
      * @covers ::_isValidCommandName
+     * @covers ::_isAbsoluteCommandPath
      */
     public function locateNonExecutableCommand()
     {
@@ -52,15 +54,35 @@ public function locateNonExecutableCommand()
     }
 
     /**
-     * Verify that a bad command name returns no result.
+     * Verify that an absolute path to a command works.
+     *
+     * @test
+     * @covers ::__construct
+     * @covers ::locate
+     * @covers ::locateAll
+     * @covers ::_getPotentialCommandLocations
+     * @covers ::_getPaths
+     * @covers ::_isValidCommandName
+     * @covers ::_isAbsoluteCommandPath
+     */
+    public function locateAbsoluteCommand()
+    {
+        $locator = new Locator(array());
+
+        $this->assertSame('/usr/bin/env', $locator->locate('/usr/bin/env'));
+    }
+
+    /**
+     * Verify that a command name that is in a subdirectory returns no result.
      *
      * @test
      * @covers ::__construct
      * @covers ::locate
      * @covers ::locateAll
      * @covers ::_isValidCommandName
+     * @covers ::_isAbsoluteCommandPath
      */
-    public function locateBadCommandName()
+    public function locateSubdirectoryCommand()
     {
         $locator = new Locator(array());
 
@@ -77,6 +99,7 @@ public function locateBadCommandName()
      * @covers ::_getPotentialCommandLocations
      * @covers ::_getPaths
      * @covers ::_isValidCommandName
+     * @covers ::_isAbsoluteCommandPath
      */
     public function locateMultipleLocations()
     {
@@ -104,6 +127,7 @@ public function locateMultipleLocations()
      * @covers ::_getPotentialCommandLocations
      * @covers ::_getPaths
      * @covers ::_isValidCommandName
+     * @covers ::_isAbsoluteCommandPath
      */
     public function locateAll()
     {