CI check to verify required exercises files exist.

.travis.yml

@@ -9,3 +9,4 @@ addons:
 
 script:
   - bin/jsonlint
+  - bin/check_required_files_present

bin/check_required_files_present

@@ -0,0 +1,55 @@
+#!/usr/bin/env bash
+MISSING_FILES=0
+SHOW_PROGRESS='false'
+
+if [ ! -d exercises ] ; then
+	echo "\"exercises\" directory not found, make sure you're running from the repository root" >&2
+	exit 1
+fi
+
+function show_progress {
+	if [ $SHOW_PROGRESS == 'true' ]; then
+		echo -n '.'
+	fi
+}
+
+function require_file {
+	filename=$1
+	if [ ! -f $filename ]; then
+		echo "required file missing: $filename" >&2
+		let "MISSING_FILES+=1"
+	fi
+}
+
+function check_directory {
+	directory=$1
+	for exercise_directory in $directory/* ; do
+		show_progress
+		require_file "$exercise_directory/description.md"
+		require_file "$exercise_directory/metadata.yml"
+	done
+
+}
+
+while : 
+do
+	case "$1" in
+		-p | --progress)
+			SHOW_PROGRESS="true"
+			shift 1
+			;;
+		*)
+			check_directory 'exercises'
+			if [ $SHOW_PROGRESS == 'true' ]; then
+				echo 
+				echo Done: $MISSING_FILES files missing.
+			fi
+			if (( $MISSING_FILES > 0 )); then
+				exit 1
+			else
+				exit 0
+			fi
+			;;
+	esac
+done
+