oetest.py: Fix problem when there is more than one json file for package extraction

This allow to have more than one test to have json file in order
to install packages in the DUT without using a package manager.

[YOCTO #9926]

(From OE-Core rev: 129c2b4589710aa24e23108f2728f1625b72cb06)

Signed-off-by: Mariano Lopez <mariano.lopez@linux.intel.com>
Signed-off-by: Ross Burton <ross.burton@intel.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/lib/oeqa/oetest.py

@@ -441,12 +441,9 @@ class RuntimeTestContext(TestContext):
 
     def extract_packages(self):
         """
-        Find and extract packages that will be needed during runtime.
+        Find packages that will be needed during runtime.
         """
 
-        needed_packages = {}
-        extracted_path = self.d.getVar("TEST_EXTRACTED_DIR", True)
-        packaged_path = self.d.getVar("TEST_PACKAGED_DIR", True)
         modules = self.getTestModules()
         bbpaths = self.d.getVar("BBPATH", True).split(":")
 
@@ -454,6 +451,15 @@ class RuntimeTestContext(TestContext):
             json_file = self._getJsonFile(module)
             if json_file:
                 needed_packages = self._getNeededPackages(json_file)
+                self._perform_package_extraction(needed_packages)
+
+    def _perform_package_extraction(self, needed_packages):
+        """
+        Extract packages that will be needed during runtime.
+        """
+
+        extracted_path = self.d.getVar("TEST_EXTRACTED_DIR", True)
+        packaged_path = self.d.getVar("TEST_PACKAGED_DIR", True)
 
         for key,value in needed_packages.items():
             packages = ()