raise error if mail isn't found in $PATH and reportemail = yes

CHANGELOG.md

@@ -7,6 +7,10 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 
+### Changed
+
+- [core] raise error if mail isn't found in $PATH and reportemail = yes
+
 ### Fixed
 
 - [build] make build reproducible regardless of usrmerge (DEBBUG-915222)

src/backupninja.in

@@ -613,6 +613,7 @@ else doit=0
 fi
 
 if [ $doit == 1 ]; then
+   if [ -x "$(which mail 2>/dev/null)" ]; then
       debug "send report to $reportemail"
       hostname=`hostname`
       [ $warnings == 0 ] || subject="WARNING"
@@ -636,6 +637,10 @@ if [ $doit == 1 ]; then
             done
          fi
       } | mail -s "backupninja: $hostname $subject" $reportemail
+   else
+      error "Unable to locate mail executable, email report not sent!"
+      let "errors += 1"
+   fi
 fi
 
 if [ $actions_run != 0 ]; then

test/backupninja.bats

 load common
 
+teardown_backupninja() {
+    [ -x /usr/bin/mail.moved ] && mv /usr/bin/mail.moved /usr/bin/mail
+}
+
 create_test_action() {
     echo '#!/bin/sh' > "${BATS_TMPDIR}/backup.d/test.sh"
     echo "$1 $2" >> "${BATS_TMPDIR}/backup.d/test.sh"
@@ -92,7 +96,7 @@ create_test_action() {
 }
 
 @test "reports: report is mailed when reportsuccess = yes" {
-    create_test_action
+    create_test_action info test_info
     setconfig backupninja.conf reportsuccess yes
     run backupninja --now -f "${BATS_TMPDIR}/backupninja.conf" --run "${BATS_TMPDIR}/backup.d/test.sh"
     sleep 0.1
@@ -109,7 +113,7 @@ create_test_action() {
 }
 
 @test "reports: success report contains disk space info" {
-    create_test_action
+    create_test_action info test_info
     echo "directory = /" >> "${BATS_TMPDIR}/backup.d/test.sh"
     setconfig backupninja.conf reportsuccess yes
     setconfig backupninja.conf reportspace yes
@@ -118,6 +122,15 @@ create_test_action() {
     grep -q "/dev/sda1" /var/mail/vagrant
 }
 
+@test "reports: emits error if mail executable is not found" {
+    create_test_action info test_info
+    setconfig backupninja.conf reportsuccess yes
+    mv /usr/bin/mail /usr/bin/mail.moved
+    run backupninja --now -f "${BATS_TMPDIR}/backupninja.conf" --run "${BATS_TMPDIR}/backup.d/test.sh"
+    [ "$status" -eq 1 ]
+    false
+}
+
 @test "scheduling: runs when = 'everyday at 01' and time matches" {
     create_test_action info test_info
     setconfig backupninja.conf when 'everyday at 01'