Implement getHeaders() and hasHeader()

Implement the remaining header methods. Use hasHeader() and
getHeaderLine internally to prevent mutation of the request
as it builds internal state where possible.

src/Network/Request.php

@@ -367,8 +367,8 @@ class Request implements ArrayAccess
             $data = $this->input();
             parse_str($data, $data);
         }
-        if ($this->env('HTTP_X_HTTP_METHOD_OVERRIDE')) {
-            $data['_method'] = $this->env('HTTP_X_HTTP_METHOD_OVERRIDE');
+        if ($this->hasHeader('X-Http-Method-Override')) {
+            $data['_method'] = $this->getHeaderLine('X-Http-Method_Override');
             $override = true;
         }
         $this->_environment['ORIGINAL_REQUEST_METHOD'] = $method;
@@ -983,6 +983,34 @@ class Request implements ArrayAccess
      */
     public function getHeaders()
     {
+        $headers = [];
+        foreach ($this->_environment as $key => $value) {
+            $name = null;
+            if (strpos($key, 'HTTP_') === 0) {
+                $name = substr($key, 5);
+            }
+            if (strpos($key, 'CONTENT_') === 0) {
+                $name = $key;
+            }
+            if ($name !== null) {
+                $name = strtr(strtolower($name), '_', ' ');
+                $name = strtr(ucwords($name), ' ', '-');
+                $headers[$name] = (array)$value;
+            }
+        }
+        return $headers;
+    }
+
+    /**
+     * Check if a header exists in the request.
+     *
+     * @param string $name The header you want to get (case-insensitive)
+     * @return bool Whether or not the header is defined.
+     */
+    public function hasHeader($name)
+    {
+        $name = $this->normalizeHeaderName($name);
+        return array_key_exists($name, $this->_environment);
     }
 
     /**

tests/TestCase/Network/RequestTest.php

@@ -1287,6 +1287,52 @@ class RequestTest extends TestCase
      *
      * @return void
      */
+    public function testGetHeaders()
+    {
+        $request = new Request(['environment' => [
+            'HTTP_HOST' => 'localhost',
+            'CONTENT_TYPE' => 'application/json',
+            'CONTENT_LENGTH' => 1337,
+            'HTTP_CONTENT_MD5' => 'abc123',
+            'HTTP_DOUBLE' => ['a', 'b']
+        ]]);
+        $headers = $request->getHeaders();
+        $expected = [
+            'Host' => ['localhost'],
+            'Content-Type' => ['application/json'],
+            'Content-Length' => [1337],
+            'Content-Md5' => ['abc123'],
+            'Double' => ['a', 'b'],
+        ];
+        $this->assertEquals($expected, $headers);
+    }
+
+    /**
+     * Test hasHeader
+     *
+     * @return void
+     */
+    public function testHasHeader()
+    {
+        $request = new Request(['environment' => [
+            'HTTP_HOST' => 'localhost',
+            'CONTENT_TYPE' => 'application/json',
+            'CONTENT_LENGTH' => 1337,
+            'HTTP_CONTENT_MD5' => 'abc123',
+            'HTTP_DOUBLE' => ['a', 'b']
+        ]]);
+        $this->assertTrue($request->hasHeader('Host'));
+        $this->assertTrue($request->hasHeader('Content-Type'));
+        $this->assertTrue($request->hasHeader('Content-MD5'));
+        $this->assertTrue($request->hasHeader('Double'));
+        $this->assertFalse($request->hasHeader('Authorization'));
+    }
+
+    /**
+     * Test getting headers with psr7 methods
+     *
+     * @return void
+     */
     public function testGetHeader()
     {
         $request = new Request(['environment' => [
@@ -2440,7 +2486,6 @@ class RequestTest extends TestCase
         $expected = $vars + [
             'CONTENT_TYPE' => null,
             'HTTP_CONTENT_TYPE' => null,
-            'HTTP_X_HTTP_METHOD_OVERRIDE' => null,
             'ORIGINAL_REQUEST_METHOD' => 'PUT',
         ];
         $this->assertSame($expected, $request->getServerParams());