Test that dnf-automatic emitters send error messages

If properly configured by "send_error_messages = yes" config option,
dnf-automatic emitters can also report errors occured during the
dnf-automatic run.

Test is for:
rpm-software-management/dnf#1918
https://issues.redhat.com/browse/RHEL-61882

dnf-behave-tests/dnf/dnf-automatic/error-report.feature

@@ -15,7 +15,7 @@ Given I delete file "/etc/yum.repos.d/*.repo" with globs
     """
 
 
-# First, install the "test-1.0" package, which should proceed successfully. 
+# First, install the "test-1.0" package, which should proceed successfully.
 # Then, attempt to update to "test-1.1", which contains a broken scriptlet.
 # An error should be reported during the installation of the update.
 @bz2170093
@@ -30,3 +30,31 @@ Scenario: dnf-automatic reports an error when package installation failed
     Error in PREIN scriptlet in rpm package test
     Error: Transaction failed
     """
+
+# https://github.com/rpm-software-management/dnf/issues/1918
+# https://issues.redhat.com/browse/RHEL-61882
+Scenario: emitters can report errors if configured by send_error_messages = yes
+  Given I use repository "dnf-ci-automatic-update"
+    And I create file "/etc/dnf/automatic.conf" with
+    """
+    [commands]
+    download_updates = yes
+    apply_updates = yes
+
+    [emitters]
+    send_error_messages = yes
+    emit_via = command_email
+
+    [command_email]
+    command_format = "echo {body} > /tmp/dnf_error"
+    """
+    And I successfully execute dnf with args "install test-1.0"
+    And file "/tmp/dnf_error" does not exist
+   When I execute dnf-automatic with args "--installupdates"
+   Then the exit code is 1
+    And Transaction is empty
+    And file "/tmp/dnf_error" matches line by line
+    """
+    An error has occured on: .*
+    Error: Transaction failed
+    """