test-lib: Also check completion exit code.

The completion may unexpectedly abort somewhere.

Additionally, reformat the failure messages (don't prepend a "*", this should be reserved to mark the individual test runs) and use "compreply" instead of "output", so that it's already clear from the diff output that the completion is being tested.

tests/test-lib.sh

@@ -305,7 +305,7 @@ $cmp_output"
 		else
 			cmp_output=$(test_cmp expect output)
 			test_failure_ "$2" "$3" "
-* expected exit code $1, actual ${eval_ret}${cmp_output:+
+expected exit code $1, actual ${eval_ret}${cmp_output:+
 }${cmp_output}"
 		fi
 	fi
@@ -324,7 +324,7 @@ test_expect_code () {
 			test_ok_ "$2"
 		else
 			test_failure_ "$2" "$3" "
-* expected exit code $1, actual ${eval_ret}"
+expected exit code $1, actual ${eval_ret}"
 		fi
 	fi
 	echo >&3 ""
@@ -658,24 +658,28 @@ test_todo_completion () {
 
 		source "$TEST_DIRECTORY/../todo_completion"
 		_todo
-
+		ret=$?
-		IFS=$'\n'
+		if [ "$ret" = 0 ]
-		printf "%s${EXPECT:+\\n}" "${EXPECT[*]}" > expect
-		printf "%s${COMPREPLY:+\\n}" "${COMPREPLY[*]}" > output
-		IFS=$SAVEIFS
-
-		if [ ${#COMPREPLY[@]} -eq ${#EXPECT[@]} ]
 		then
-			if [ "${COMPREPLY[*]}" = "${EXPECT[*]}" ]
+			IFS=$'\n'
+			printf "%s${EXPECT:+\\n}" "${EXPECT[*]}" > expect
+			printf "%s${COMPREPLY:+\\n}" "${COMPREPLY[*]}" > compreply
+			IFS=$SAVEIFS
+
+			if [ ${#COMPREPLY[@]} -eq ${#EXPECT[@]} ]
 			then
-				test_ok_ "$description"
+				if [ "${COMPREPLY[*]}" = "${EXPECT[*]}" ]
+				then
+					test_ok_ "$description"
+				else
+					test_failure_ "$description" "$(test_cmp expect compreply)"
+				fi
 			else
-				test_failure_ "$description" "Differing completion(s):
+				test_failure_ "$description" "expected ${#EXPECT[@]} completion(s), got ${#COMPREPLY[@]}:
-$(test_cmp expect output)"
+$(test_cmp expect compreply)"
 			fi
 		else
-			test_failure_ "$description" "Expected ${#EXPECT[@]} completion(s), got ${#COMPREPLY[@]}:
+			test_failure_ "$description" "expected completions, actual exit code $ret"
-$(test_cmp expect output)"
 		fi
 	fi
 	echo >&3 ""