From a153ec5951ac4dbf2cb8e465c349326a9d4a132e Mon Sep 17 00:00:00 2001
From: Miccah <m.castorina93@gmail.com>
Date: Fri, 19 Feb 2021 04:43:18 -0600
Subject: [PATCH] cli: ensure that required flags are set (#8826)

---
 examples/cli.v          | 14 +++++++-------
 vlib/cli/command.v      |  2 +-
 vlib/cli/command_test.v | 17 +++++++++++++++++
 3 files changed, 25 insertions(+), 8 deletions(-)

diff --git a/examples/cli.v b/examples/cli.v
index 3a80e78d19..66a8eb21d1 100644
--- a/examples/cli.v
+++ b/examples/cli.v
@@ -32,17 +32,17 @@ fn main() {
 		description: 'Number of times the message gets printed.'
 	})
 	greet_cmd.add_flag(Flag{
-	 	flag: .string
-	 	name: 'fun'
-	 	multiple: true
-	 	description: 'Just a dumby flags to show multiple.'
+		flag: .string
+		name: 'fun'
+		multiple: true
+		description: 'Just a dumby flags to show multiple.'
 	})
 	cmd.add_command(greet_cmd)
 	cmd.setup()
 	cmd.parse(os.args)
 }
 
-fn greet_func(cmd Command) {
+fn greet_func(cmd Command) ? {
 	language := cmd.flags.get_string('language') or {
 		panic('Failed to get `language` flag: $err')
 	}
@@ -76,10 +76,10 @@ fn greet_func(cmd Command) {
 	}
 }
 
-fn greet_pre_func(cmd Command) {
+fn greet_pre_func(cmd Command) ? {
 	println('This is a function running before the main function.\n')
 }
 
-fn greet_post_func(cmd Command) {
+fn greet_post_func(cmd Command) ? {
 	println('\nThis is a function running after the main function.')
 }
diff --git a/vlib/cli/command.v b/vlib/cli/command.v
index 92c0a55764..69467bcf2a 100644
--- a/vlib/cli/command.v
+++ b/vlib/cli/command.v
@@ -267,7 +267,7 @@ fn (cmd Command) check_version_flag() {
 
 fn (cmd Command) check_required_flags() {
 	for flag in cmd.flags {
-		if flag.required && flag.value.len > 0 {
+		if flag.required && flag.value.len == 0 {
 			full_name := cmd.full_name()
 			println('Flag `$flag.name` is required by `$full_name`')
 			exit(1)
diff --git a/vlib/cli/command_test.v b/vlib/cli/command_test.v
index 7543f9c09c..aae7199c85 100644
--- a/vlib/cli/command_test.v
+++ b/vlib/cli/command_test.v
@@ -117,6 +117,23 @@ fn test_if_multiple_flags_get_set() {
 	cmd.parse(['command', '-flag', 'value', '-value', '42'])
 }
 
+fn test_if_required_flags_get_set() {
+	mut cmd := cli.Command{
+		name: 'command'
+		execute: flag_should_have_value_of_42
+	}
+	cmd.add_flag(cli.Flag{
+		flag: .string
+		name: 'flag'
+	})
+	cmd.add_flag(cli.Flag{
+		flag: .int
+		name: 'value'
+		required: true
+	})
+	cmd.parse(['command', '-flag', 'value', '-value', '42'])
+}
+
 fn flag_is_set_in_subcommand(cmd cli.Command) ? {
 	flag := cmd.flags.get_string('flag') or { panic(err) }
 	assert flag == 'value'