docker_run: run docker_build if the image does not exist

As an effort to make cqfd run similarily to known tools, such as
sudo, the docker image is automatically built if necessary rather
than dying.

README.md

@@ -21,7 +21,6 @@ Just follow these steps:
 * Go into your project's directory
 * Create a .cqfdrc file
 * Put a Dockerfile and save it as .cqfd/docker/Dockerfile
-* Run ``cqfd --init``
 
 Examples are available in the samples/ directory.
 

cqfd

@@ -187,9 +187,8 @@ docker_build() {
 # arg$1: the command string to execute as $cqfd_user
 #
 docker_run() {
-
 	if ! docker image inspect $docker_img_name &> /dev/null; then
-		die "The docker image doesn't exist, launch 'cqfd --init' to create it"
+		docker_build
 	fi
 
 	local interactive_options

tests/05-cqfd_run

@@ -42,8 +42,11 @@ done
 ################################################################################
 jtest_prepare "Modifying the Dockerfile should require running 'cqfd --init' again"
 dockerfile=.cqfd/docker/Dockerfile
+prev_img_count=$(docker images | grep cqfd_test | wc -l)
 echo "RUN echo $RANDOM" >> $dockerfile
-if $TDIR/.cqfd/cqfd; then
+$cqfd
+new_img_count=$(docker images | grep cqfd_test | wc -l)
+if [ "$prev_img_count" -eq "$new_img_count" ]; then
   jtest_result fail
 else
   jtest_result pass