Merge branch 'ds/coverage-diff'

The result of coverage test can be combined with "git blame" to
check the test coverage of code introduced recently with a new
'coverage-diff' tool (in contrib/).

* ds/coverage-diff:
  contrib: add coverage-diff script

Author: gitster

contrib/coverage-diff.sh

@@ -0,0 +1,108 @@
+#!/bin/sh
+
+# Usage: Run 'contrib/coverage-diff.sh <version1> <version2>' from source-root
+# after running
+#
+#     make coverage-test
+#     make coverage-report
+#
+# while checked out at <version2>. This script combines the *.gcov files
+# generated by the 'make' commands above with 'git diff <version1> <version2>'
+# to report new lines that are not covered by the test suite.
+
+V1=$1
+V2=$2
+
+diff_lines () {
+	perl -e '
+		my $line_num;
+		while (<>) {
+			# Hunk header?  Grab the beginning in postimage.
+			if (/^@@ -\d+(?:,\d+)? \+(\d+)(?:,\d+)? @@/) {
+				$line_num = $1;
+				next;
+			}
+
+			# Have we seen a hunk?  Ignore "diff --git" etc.
+			next unless defined $line_num;
+
+			# Deleted line? Ignore.
+			if (/^-/) {
+				next;
+			}
+
+			# Show only the line number of added lines.
+			if (/^\+/) {
+				print "$line_num\n";
+			}
+			# Either common context or added line appear in
+			# the postimage.  Count it.
+			$line_num++;
+		}
+	'
+}
+
+files=$(git diff --name-only "$V1" "$V2" -- \*.c)
+
+# create empty file
+>coverage-data.txt
+
+for file in $files
+do
+	git diff "$V1" "$V2" -- "$file" |
+	diff_lines |
+	sort >new_lines.txt
+
+	if ! test -s new_lines.txt
+	then
+		continue
+	fi
+
+	hash_file=$(echo $file | sed "s/\//\#/")
+
+	if ! test -s "$hash_file.gcov"
+	then
+		continue
+	fi
+
+	sed -ne '/#####:/{
+			s/    #####://
+			s/:.*//
+			s/ //g
+			p
+		}' "$hash_file.gcov" |
+	sort >uncovered_lines.txt
+
+	comm -12 uncovered_lines.txt new_lines.txt |
+	sed -e 's/$/\)/' |
+	sed -e 's/^/ /' >uncovered_new_lines.txt
+
+	grep -q '[^[:space:]]' <uncovered_new_lines.txt &&
+	echo $file >>coverage-data.txt &&
+	git blame -s "$V2" -- "$file" |
+	sed 's/\t//g' |
+	grep -f uncovered_new_lines.txt >>coverage-data.txt &&
+	echo >>coverage-data.txt
+
+	rm -f new_lines.txt uncovered_lines.txt uncovered_new_lines.txt
+done
+
+cat coverage-data.txt
+
+echo "Commits introducing uncovered code:"
+
+commit_list=$(cat coverage-data.txt |
+	grep -E '^[0-9a-f]{7,} ' |
+	awk '{print $1;}' |
+	sort |
+	uniq)
+
+(
+	for commit in $commit_list
+	do
+		git log --no-decorate --pretty=format:'%an      %h: %s' -1 $commit
+		echo
+	done
+) | sort
+
+rm coverage-data.txt