help: deduplicate 'pro help' command entries

We use a class variable to make sure each command can register its own
help entry to the main help page. When get_parser is called more than
once, the subparsers are instance bound but the help content gets
duplicated. We now make sure to only add entries that are not present
yet.

Signed-off-by: Renan Rodrigo <[email protected]>

features/cli/help.feature

@@ -8,6 +8,45 @@ Feature: Pro Client help text
       """
       usage: pro [-h] [--debug] [--version] <command> ...
 
+      Quick start commands:
+
+        status           current status of all Ubuntu Pro services
+        attach           attach this machine to an Ubuntu Pro subscription
+        enable           enable a specific Ubuntu Pro service on this machine
+        system           show system information related to Pro services
+        security-status  list available security updates for the system
+
+      Security-related commands:
+
+        fix              check for and mitigate the impact of a CVE/USN on this system
+
+      Troubleshooting-related commands:
+
+        collect-logs     collect Pro logs and debug information
+
+      Other commands:
+
+        api              Calls the Client API endpoints.
+        auto-attach      automatically attach on supported platforms
+        config           manage Ubuntu Pro configuration on this machine
+        detach           remove this machine from an Ubuntu Pro subscription
+        disable          disable a specific Ubuntu Pro service on this machine
+        refresh          refresh Ubuntu Pro services
+
+      Flags:
+
+        -h, --help       Displays help on pro and command line options
+        --debug          show all debug log messages to console
+        --version        show version of pro
+
+      Use pro <command> --help for more information about a command.
+      """
+    # '--help' and 'help' should both work and produce the same output
+    When I run `pro help` as non-root
+    Then I will see the following on stdout
+      """
+      usage: pro [-h] [--debug] [--version] <command> ...
+
       Quick start commands:
 
         status           current status of all Ubuntu Pro services

uaclient/cli/parser.py

@@ -52,9 +52,11 @@ def add_help_entry(
         help_string: str,
         position: int = 0,
     ):
-        cls.help_entries[category].append(
-            HelpEntry(position=position, name=name, help_string=help_string)
+        entry = HelpEntry(
+            position=position, name=name, help_string=help_string
         )
+        if entry not in cls.help_entries[category]:
+            cls.help_entries[category].append(entry)
 
     def __init__(self, *args, use_main_help: bool = True, **kwargs):
         super().__init__(*args, **kwargs)