docs(grades): fix test and error message

sh/tests/grades_test.sh

@@ -5,8 +5,9 @@ IFS='
 script_dirS=$(cd -P "$(dirname "$BASH_SOURCE")" &>/dev/null && pwd)
 
 challenge() {
-    args=$1
-    input=$2
+
+    input="${@: -1}"
+    args=${@:1:$#-1}
 
     submitted=$(
         bash -c ""$script_dirS"/student/grades.sh $args" <<EOF
@@ -23,9 +24,8 @@ EOF
     if [ $? != 0 ]; then
         exit 1
     fi
-    echo $submitted
-    echo $expected
 }
+
 challenge 1 "Student1
 90
 "
@@ -83,3 +83,6 @@ not_good
 challenge 1 "Student1
 -75
 "
+challenge 1 1 "Louis
+20
+"

sh/tests/solutions/grades.sh

@@ -4,7 +4,7 @@ num_students=$1
 declare -a students
 
 if [ $# -ne 1 ]; then
-    echo "Error: Expect 1 argument only!"
+    echo "Error: expect 1 argument only!"
     exit 1
 fi
 

subjects/devops/grades/README.md

@@ -66,7 +66,7 @@ Student Name #1: Bob
 Student Grade #1: ten
 Error: The grade 'ten' is not a valid input. Only numerical grades between 0 and 100 are accepted.
 $ ./grades.sh 1 2 3
-Error: Expect 1 argument only!
+Error: expect 1 argument only!
 $
 ```