Add TestDefaults.set_to.

Makes it easier for custom parsers (#1283) to set defaults to test.

atest/testdata/parsing/custom/CustomParser.py

@@ -27,10 +27,7 @@ def parse(self, source: Path, defaults: TestDefaults) -> TestSuite:
             return 'bad'
         suite = custom.parse(source)
         for test in suite.tests:
-            test.tags += defaults.tags
-            test.setup = defaults.setup
-            test.teardown = defaults.teardown
-            test.timeout = defaults.timeout
+            defaults.set_to(test)
         return suite
 
     def parse_init(self, source: Path, defaults: TestDefaults) -> TestSuite:

src/robot/running/builder/settings.py

@@ -24,7 +24,7 @@
 
 from robot.model import Tags
 
-from ..model import Keyword
+from ..model import Keyword, TestCase
 
 
 class KeywordDict(TypedDict):
@@ -111,6 +111,21 @@ def timeout(self) -> 'str|None':
     def timeout(self, timeout: 'str|None'):
         self._timeout = timeout
 
+    def set_to(self, test: TestCase):
+        """Sets defaults to the given test.
+
+        Tags are always added to the test. Setup, teardown and timeout are
+        set only if the test does not have them set initially.
+        """
+        if self.tags:
+            test.tags += self.tags
+        if self.setup and not test.has_setup:
+            test.setup = self.setup
+        if self.teardown and not test.has_teardown:
+            test.teardown = self.teardown
+        if self.timeout and not test.timeout:
+            test.timeout = self.timeout
+
 
 class FileSettings: