safer tests for no ppm loader

Author: jcupitt

tests/ConfigTest.php

@@ -43,10 +43,12 @@ public function testPpmLoadBuffer()
 0 0 0 
 ";
 
-        // the PPM loader is built in and should be available in most 
-        // libvips binaries
-        $image = Vips\Image::ppmload_buffer($ppm);
-        $this->assertTrue($image->width == 1);
+        if (Vips\Utils::typeFromName("VipsForeignLoadPpm") != 0) {
+            // the PPM loader is built in and should be available in most 
+            // libvips binaries
+            $image = Vips\Image::ppmload_buffer($ppm);
+            $this->assertTrue($image->width == 1);
+        }
     }
 
     public function testBlockUntrusted()
@@ -57,7 +59,8 @@ public function testBlockUntrusted()
 0 0 0 
 ";
 
-        if (Vips\FFI::atLeast(8, 13)) {
+        if (Vips\FFI::atLeast(8, 13) &&
+            Vips\Utils::typeFromName("VipsForeignLoadPpm") != 0) {
             Vips\Config::setBlockUntrusted(true);
 
             // should fail
@@ -75,7 +78,8 @@ public function testBlock()
 0 0 0 
 ";
 
-        if (Vips\FFI::atLeast(8, 13)) {
+        if (Vips\FFI::atLeast(8, 13) &&
+            Vips\Utils::typeFromName("VipsForeignLoadPpm") != 0) {
             Vips\Config::setBlockUntrusted(true);
             Vips\Config::setBlock("VipsForeignLoadPpm", false);