add unit test framework with gcov coverage support (make check-coverage)

This is what it looks like

==============================================================================
Test coverage for module polkit:
==============================================================================
polkit-sysdeps.c                                        :   0% (0 of 38)
polkit-error.c                                          :   0% (0 of 44)
polkit-result.c                                         :   0% (0 of 16)
polkit-context.c                                        :   0% (0 of 213)
polkit-action.c                                         :  34% (20 of 58)
polkit-seat.c                                           :   0% (0 of 34)
polkit-session.c                                        :   0% (0 of 97)
polkit-caller.c                                         :   0% (0 of 81)
polkit-policy-file-entry.c                              :   0% (0 of 72)
polkit-policy-file.c                                    :   0% (0 of 220)
polkit-policy-cache.c                                   :   0% (0 of 98)
polkit-policy-default.c                                 :   0% (0 of 67)
polkit-debug.c                                          :   0% (0 of 15)
polkit-utils.c                                          :   0% (0 of 42)
polkit-config.c                                         :   0% (0 of 263)
polkit-authorization.c                                  :   0% (0 of 162)
polkit-authorization-constraint.c                       :   0% (0 of 107)
polkit-authorization-db.c                               :   0% (0 of 222)

Source lines          : 6919
Actual statements     : 1849
Executed statements   : 20
Test coverage         : 1%

2 files changed, 62 insertions, 0 deletions

diff --git a/test/Makefile.am b/test/Makefile.am
new file mode 100644
index 0000000..b37166c
--- /dev/null
+++ b/test/Makefile.am
@@ -0,0 +1,5 @@
+
+EXTRA_DIST = create-coverage-report.sh
+
+clean-local :
+	rm -f *~
diff --git a/test/create-coverage-report.sh b/test/create-coverage-report.sh
new file mode 100755
index 0000000..336a5bd
--- /dev/null
+++ b/test/create-coverage-report.sh
@@ -0,0 +1,57 @@
+#!/bin/sh
+
+TOTAL_ACTUAL=0
+TOTAL_COVERED=0
+TOTAL_SOURCE=0
+
+MODULE=$1
+shift
+
+echo "=============================================================================="
+echo "Test coverage for module $MODULE:"
+echo "=============================================================================="
+
+while [ $# -gt 0 ] ; do
+    gcov $1 -o .libs/ > /dev/null
+
+    SOURCE=`cat $1 |wc -l`
+    ACTUAL=`grep -v "        -:" $1.gcov  |wc -l`
+    NOT_COVERED=`grep "    #####:" $1.gcov  |wc -l`
+    COVERED=$(($ACTUAL - $NOT_COVERED))
+    PERCENT=$((100 * $COVERED / $ACTUAL))
+
+    TOTAL_SOURCE=$(($TOTAL_SOURCE + $SOURCE))
+    TOTAL_ACTUAL=$(($TOTAL_ACTUAL + $ACTUAL))
+    TOTAL_COVERED=$(($TOTAL_COVERED + $COVERED))
+
+    echo -n "$1"
+
+    n=${#1}
+    while [ $n -lt 55 ] ; do
+        echo -n " "
+        n=$(($n + 1))
+    done
+
+    echo -n " : "
+
+    if [ $PERCENT -lt 10 ] ; then
+        echo -n "  $PERCENT%"
+    elif [ $PERCENT -lt 100 ] ; then
+        echo -n " $PERCENT%"
+    else
+        echo -n "100%"
+    fi
+
+    echo " ($COVERED of $ACTUAL)"
+
+    shift
+done
+
+TOTAL_PERCENT=$((100 * $TOTAL_COVERED / $TOTAL_ACTUAL))
+
+echo
+echo "Source lines          : $TOTAL_SOURCE"
+echo "Actual statements     : $TOTAL_ACTUAL"
+echo "Executed statements   : $TOTAL_COVERED"
+echo "Test coverage         : $TOTAL_PERCENT%"
+echo