From e096111ef669c0425686ac87c7e60d6686032ebe Mon Sep 17 00:00:00 2001
From: Lars Uebernickel <lars.uebernickel@canonical.com>
Date: Wed, 23 Jan 2013 20:05:45 +0100
Subject: Add trim-lcov.py

It strips some unreachable branches from the coverage reports, such as
g_return_if_fail.
---
 Makefile.am.coverage |  4 +++-
 trim-lcov.py         | 53 ++++++++++++++++++++++++++++++++++++++++++++++++++++
 2 files changed, 56 insertions(+), 1 deletion(-)
 create mode 100755 trim-lcov.py

diff --git a/Makefile.am.coverage b/Makefile.am.coverage
index fb97747..dc3b9c8 100644
--- a/Makefile.am.coverage
+++ b/Makefile.am.coverage
@@ -1,6 +1,8 @@
 
 # Coverage targets
 
+EXTRA_DIST = trim-lcov.py
+
 .PHONY: clean-gcno clean-gcda \
 	coverage-html generate-coverage-html clean-coverage-html \
 	coverage-gcovr generate-coverage-gcovr clean-coverage-gcovr
@@ -23,7 +25,7 @@ coverage-html: clean-gcda
   
 generate-coverage-html:
 	@echo Collecting coverage data
-	$(LCOV) --directory $(top_builddir) --capture --output-file coverage.info --no-checksum --compat-libtool
+	$(LCOV) --directory $(top_builddir) --capture --no-checksum --compat-libtool | $(top_srcdir)/trim-lcov.py > coverage.info
 	LANG=C $(GENHTML) --prefix $(top_builddir) --output-directory coveragereport --title "Code Coverage" --legend --show-details coverage.info
   
 clean-coverage-html: clean-gcda
diff --git a/trim-lcov.py b/trim-lcov.py
new file mode 100755
index 0000000..c1709c3
--- /dev/null
+++ b/trim-lcov.py
@@ -0,0 +1,53 @@
+#!/usr/bin/python
+
+# This script removes branch and/or line coverage data for lines that
+# contain a particular substring.
+#
+# In the interest of "fairness" it removes all branch or coverage data
+# when a match is found -- not just negative data.  It is therefore
+# likely that running this script will actually reduce the total number
+# of lines and branches that are marked as covered (in absolute terms).
+#
+# This script intentionally avoids checking for errors.  Any exceptions
+# will trigger make to fail.
+#
+# Author: Ryan Lortie <desrt@desrt.ca>
+
+import sys
+
+line_suppress = ['g_assert_not_reached']
+branch_suppress = ['g_assert', 'g_return_if_fail', 'g_return_val_if_fail', 'G_DEFINE_TYPE']
+
+def check_suppress(suppressions, source, data):
+    line, _, rest = data.partition(',')
+    line = int(line) - 1
+
+    assert line < len(source)
+
+    for suppression in suppressions:
+        if suppression in source[line]:
+            return True
+
+    return False
+
+source = []
+for line in sys.stdin:
+    line = line[:-1]
+
+    keyword, _, rest = line.partition(':')
+
+    # Source file
+    if keyword == 'SF':
+        source = file(rest).readlines()
+
+    # Branch coverage data
+    elif keyword == 'BRDA':
+        if check_suppress(branch_suppress, source, rest):
+            continue
+
+    # Line coverage data
+    elif keyword == 'DA':
+        if check_suppress(line_suppress, source, rest):
+            continue
+
+    print line
-- 
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