scripts: twisterlib: coverage: fix multiple branch excludes

Multiple values for `--exclude-branches-by-pattern` will result in only
the last value taking effect. Resolve this by merging all the provided
regex patterns into a single pattern with the `|` operator.

Signed-off-by: Jordan Yates <[email protected]>

Author: JordanYates

scripts/pylib/twister/twisterlib/coverage.py

@@ -330,7 +330,10 @@ def _generate(self, outdir, coveragelog):
         ztestfile = os.path.join(outdir, "ztest.json")
 
         excludes = Gcovr._interleave_list("-e", self.ignores)
-        excludes += Gcovr._interleave_list("--exclude-branches-by-pattern", self.ignore_branch_patterns)
+        if len(self.ignore_branch_patterns) > 0:
+            # Last pattern overrides previous values, so merge all patterns together
+            merged_regex = "|".join([f"({p})" for p in self.ignore_branch_patterns])
+            excludes += ["--exclude-branches-by-pattern", merged_regex]
 
         # Different ifdef-ed implementations of the same function should not be
         # in conflict treated by GCOVR as separate objects for coverage statistics.