refactor tedge flows tests which use journactl

Signed-off-by: reubenmiller <reuben.d.miller@gmail.com>

Author: reubenmiller

tests/RobotFramework/tests/tedge_flows/flows/journalctl-cursor.toml

@@ -1,5 +1,11 @@
 [input.process]
-command = "sudo journalctl --no-pager --cursor-file=/tmp/tedge-agent-cursor --unit tedge-agent"
+# Each interval, get the next 5 log messages for a given service
+# Use a cursor-file (built-in journalctl functionality) to remember the last
+# log entry processed.
+#
+# The output is piped to grep to filter out the "No entries" output from journalctl,
+# and then finally piped to cat to avoid exiting with a non-zero exit code.
+command = """sh -c "sudo journalctl --no-pager --cursor-file=/tmp/tedge-agent-cursor --unit tedge-agent -n 5 -b | grep -v '^-- No entries --$' | cat""""
 interval = "1s"
 
 [[steps]]

tests/RobotFramework/tests/tedge_flows/tedge_flows.robot

@@ -97,14 +97,17 @@ Running tedge-flows
 
 Consuming messages from a process stdout
     # Assuming the flow journalctl-follow.toml has been properly installed
-    Execute Command    (sleep 1; systemctl restart tedge-agent)&
-    Execute Command    tedge mqtt sub log/journalctl-follow --duration 2s | grep 'INFO Runtime: Running'
+    ${test_start}    Get Unix Timestamp
+    Restart Service    tedge-agent
+    ${messages}    Should Have MQTT Messages    topic=log/journalctl-follow    minimum=1    date_from=${test_start}
+    Should Not Be Empty    ${messages[0]}    msg=Output should not be empty lines
 
 Consuming messages from a process stdout, periodically
     # Assuming the flow journalctl-cursor.toml has been properly installed
-    Execute Command    (sleep 1; systemctl restart tedge-agent)&
-    Execute Command    tedge mqtt sub log/journalctl-cursor --duration 2s | grep 'INFO Runtime: Running'
-    Execute Command    tedge mqtt sub log/journalctl-cursor --duration 1s | grep 'No entries'
+    ${test_start}    Get Unix Timestamp
+    Restart Service    tedge-agent
+    ${messages}    Should Have MQTT Messages    topic=log/journalctl-cursor    minimum=10    date_from=${test_start}
+    Should Not Be Empty    ${messages[0]}    msg=Output should not be empty lines
 
 Consuming messages from the tail of file
     # Assuming the flow tail-named-pipe.toml has been properly installed
@@ -118,7 +121,8 @@ Consuming messages from a file, periodically
     Execute Command    echo world >/tmp/file.input
     Execute Command    tedge mqtt sub test/file/input --duration 1s | grep world
     Execute Command    rm /tmp/file.input
-    Execute Command    tedge mqtt sub test/file/input --duration 1s | grep 'Error in /etc/tedge/flows/read-file-periodically.toml'
+    Execute Command
+    ...    tedge mqtt sub test/file/input --duration 1s | grep 'Error in /etc/tedge/flows/read-file-periodically.toml'
     Execute Command    echo 'hello world' >/tmp/file.input
     Execute Command    tedge mqtt sub test/file/input --duration 1s | grep 'hello world'