display expected output on mismatch

check for invalid argument and terminal's color capability, use command to override aliases/functions

Author: learnbyexample

exercises/GNU_grep/solve

@@ -3,11 +3,19 @@ ref_file="../.ref_solutions/$dir_name.txt"
 sol_file="../$dir_name.txt"
 tmp_file='../.tmp.txt'
 
-# color output - need to check if Terminal supports!
-red=$(tput setaf 1)
-green=$(tput setaf 2)
-blue=$(tput setaf 4)
-clr_color=$(tput sgr0)
+# color output
+tcolors=$(tput colors)
+if [[ -n $tcolors && $tcolors -ge 8 ]]; then
+    red=$(tput setaf 1)
+    green=$(tput setaf 2)
+    blue=$(tput setaf 4)
+    clr_color=$(tput sgr0)
+else
+    red=''
+    green=''
+    blue=''
+    clr_color=''
+fi
 
 sub_sol=0
 if [[ $1 == -s ]]; then
@@ -18,10 +26,14 @@ elif [[ $1 == -q ]]; then
     # or show only the (unanswered)? question to be solved next
     cat "$sol_file"
     return
+elif [[ -n $1 ]]; then
+    echo -e 'Unknown option...Exiting script'
+    return
 fi
 
 count=0
 sol_count=0
+err_count=0
 while IFS= read -u3 -r ref_line && read -u4 -r sol_line; do
     if [[ "${ref_line:0:9}" == Solution: ]]; then
         (( count++ ))
@@ -31,7 +43,7 @@ while IFS= read -u3 -r ref_line && read -u4 -r sol_line; do
             sub_sol=0
         fi
 
-        if [[ $(eval "${ref_line:10}") == $(eval "$sol_line") ]]; then
+        if [[ $(eval "command ${ref_line:10}") == $(eval "command $sol_line") ]]; then
             (( sol_count++ ))
             # use color if terminal supports
             echo '---------------------------------------------'
@@ -40,6 +52,14 @@ while IFS= read -u3 -r ref_line && read -u4 -r sol_line; do
             echo "${green}Reference solution:${clr_color} ${ref_line:10}"
             echo '---------------------------------------------'
         else
+            (( err_count++ ))
+            if [[ $err_count == 1 && -n $sol_line ]]; then
+                echo '---------------------------------------------'
+                echo "Mismatch for question $count:"
+                echo "$(tput bold)${red}Expected output is:${clr_color}$(tput rmso)"
+                eval "command ${ref_line:10}"
+                echo '---------------------------------------------'
+            fi
             sol_line=''
         fi
     fi