twister: Adjust platform selection logic for platform_allow

In CI we typically build for "default" platforms.  However some
testcases that set "platform_allow" may have no overlap with the default
platforms and thus thoses testcases will not get built.

Change the platform selection logic in these cases to set the platforms
to the list of allowed platforms ("platform_allow") in the testcase.

Signed-off-by: Kumar Gala <[email protected]>

Author: galak

scripts/pylib/twister/twisterlib.py

@@ -3055,6 +3055,18 @@ def apply_filters(self, **kwargs):
             else:
                 platform_scope = platforms
 
+            integration = self.integration and tc.integration_platforms
+
+            # If there isn't any overlap between the platform_allow list and the platform_scope
+            # we set the scope to the platform_allow list
+            if tc.platform_allow and not platform_filter and not integration:
+                a = set(platform_scope)
+                b = set(filter(lambda item: item.name in tc.platform_allow, self.platforms))
+                c = a.intersection(b)
+                if not c:
+                    platform_scope = list(filter(lambda item: item.name in tc.platform_allow, \
+                                             self.platforms))
+
             # list of instances per testcase, aka configurations.
             instance_list = []
             for plat in platform_scope:
@@ -3163,7 +3175,6 @@ def apply_filters(self, **kwargs):
             if not instance_list:
                 continue
 
-            integration = self.integration and tc.integration_platforms
             # if twister was launched with no platform options at all, we
             # take all default platforms
             if default_platforms and not tc.build_on_all and not integration:
@@ -3175,7 +3186,7 @@ def apply_filters(self, **kwargs):
                         aa = list(filter(lambda tc: tc.platform.name in c, instance_list))
                         self.add_instances(aa)
                     else:
-                        self.add_instances(instance_list[:1])
+                        self.add_instances(instance_list)
                 else:
                     instances = list(filter(lambda tc: tc.platform.default, instance_list))
                     self.add_instances(instances)