diff --git a/sh/tests/grades_test.sh b/sh/tests/grades_test.sh
index 6e0e9e71e..1f6a1bda1 100755
--- a/sh/tests/grades_test.sh
+++ b/sh/tests/grades_test.sh
@@ -19,6 +19,12 @@ $input
 EOF
     )
     diff <(echo "$submitted") <(echo "$expected")
+
+    if [ $? != 0 ]; then
+        exit 1
+    fi
+    echo $submitted
+    echo $expected
 }
 challenge 1 "Student1
 90
@@ -41,6 +47,11 @@ challenge 1 "Student6
 challenge 1 "Student7
 25
 "
+challenge 2 "Student1
+0
+Alice
+100
+"
 challenge 3 "Bob
 90
 Alice
@@ -66,3 +77,9 @@ Alice
 Eve
 55
 "
+challenge 1 "Student1
+not_good
+"
+challenge 1 "Student1
+-75
+"
diff --git a/subjects/devops/grades/README.md b/subjects/devops/grades/README.md
index a1f8db4e5..5b57cff8a 100644
--- a/subjects/devops/grades/README.md
+++ b/subjects/devops/grades/README.md
@@ -15,6 +15,7 @@ $ ./grades.sh 1
 Student Name #1: Sara
 Student Grade #1: 90
 Sara: You did an excellent job!
+$
 ```
 
 - If the student grade is anything equal or greater than 70 you will return the string `"<name>: You did a good job!"`:
@@ -24,6 +25,7 @@ $ ./grades.sh 1
 Student Name #1: Sara
 Student Grade #1: 75
 Sara: You did a good job!
+$
 ```
 
 - If the student grade is anything equal or greater than 50 you will return the string `"<name>: You need a bit more effort!"`:
@@ -33,6 +35,7 @@ $ ./grades.sh 1
 Student Name #1: Sara
 Student Grade #1: 51
 Sara: You need a bit more effort!
+$
 ```
 
 - If the student grade is anything lower than 50 you will return the string `"<name>: You had a poor performance!"`:
@@ -42,6 +45,7 @@ $ ./grades.sh 1
 Student Name #1: Sara
 Student Grade #1: 34
 Sara: You had a poor performance!
+$
 ```
 
 ### Error handling
@@ -57,7 +61,7 @@ $ ./grades.sh 2
 Student Name #1: Sara
 Student Grade #1: 101
 Error: The grade '101' is not a valid input. Only numerical grades between 0 and 100 are accepted.
-./grades.sh 2
+$ ./grades.sh 2
 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.
@@ -82,6 +86,7 @@ Sara: You had a poor performance!
 Norman: You need a bit more effort!
 James: You did a good job!
 Albert: You did an excellent job!
+$
 ```
 
 ### Hints