refactor: move a test helper to CoverageTest

2 files changed, 10 insertions, 6 deletions

diff --git a/tests/coveragetest.py b/tests/coveragetest.py
index 8541ed28..aae4df08 100644
--- a/tests/coveragetest.py
+++ b/tests/coveragetest.py
@@ -433,6 +433,14 @@ class CoverageTest(
         return {os.path.basename(filename): filename
                 for filename in coverage_data.measured_files()}
 
+    def get_missing_arc_description(self, cov, start, end):
+        """Get the missing-arc description for a line arc in a coverage run."""
+        # ugh, unexposed methods??
+        filename = self.last_module_name + ".py"
+        fr = cov._get_file_reporter(filename)
+        arcs_executed = cov._analyze(filename).arcs_executed()
+        return fr.missing_arc_description(start, end, arcs_executed)
+
 
 class UsingModulesMixin:
     """A mixin for importing modules from tests/modules and tests/moremodules."""
diff --git a/tests/test_arcs.py b/tests/test_arcs.py
index b2d75377..5059fdc7 100644
--- a/tests/test_arcs.py
+++ b/tests/test_arcs.py
@@ -1583,14 +1583,10 @@ class MiscArcTest(CoverageTest):
             arcz=".1 17 7.  .2 23 34 45 5.  -22 2-2  -33 3-3  -44 4-4",
             arcz_missing="3-3 -44 4-4",
         )
-        # ugh, unexposed methods??
-        filename = self.last_module_name + ".py"
-        fr = cov._get_file_reporter(filename)
-        arcs_executed = cov._analyze(filename).arcs_executed()
         expected = "line 3 didn't finish the generator expression on line 3"
-        assert expected == fr.missing_arc_description(3, -3, arcs_executed)
+        assert self.get_missing_arc_description(cov, 3, -3) == expected
         expected = "line 4 didn't run the generator expression on line 4"
-        assert expected == fr.missing_arc_description(4, -4, arcs_executed)
+        assert self.get_missing_arc_description(cov, 4, -4) == expected
 
 
 class DecoratorArcTest(CoverageTest):