Provide mapping between results and tests for easier reporting

tmt/steps/execute/__init__.py

@@ -1169,3 +1169,29 @@ def results(self) -> list["tmt.result.Result"]:
         https://tmt.readthedocs.io/en/latest/spec/plans.html#execute
         """
         return self._results
+
+    def results_for_tests(self, tests: list['tmt.base.Test']) \
+            -> list[tuple[Optional[Result], Optional['tmt.base.Test']]]:
+        """
+        Collect results and corresponding tests.
+
+        :returns: a list of result and test pairs.
+            * if there is not test found for the result, e.g. when
+            results were loaded from storage but tests were not,
+            ``None`` represents the missing test: ``(result, None)``.
+            * if there is no result for a test, e.g. when the test was
+            not executed, ``None`` represents the missing result:
+            ``(None, test)``.
+        """
+
+        known_serial_numbers = {test.serial_number: test for test in tests}
+        referenced_serial_numbers = {result.serial_number for result in self._results}
+
+        return [
+            (result, known_serial_numbers.get(result.serial_number))
+            for result in self._results
+            ] + [
+            (None, test)
+            for test in tests
+            if test.serial_number not in referenced_serial_numbers
+            ]