enforce required flags (#502)

command_test.go

@@ -438,3 +438,51 @@ func TestTraverseWithBadChildFlag(t *testing.T) {
 		t.Fatalf("wrong command %q expected %q", c.Name(), sub.Name())
 	}
 }
+
+func TestRequiredFlags(t *testing.T) {
+	c := &Command{Use: "c", Run: func(*Command, []string) {}}
+	output := new(bytes.Buffer)
+	c.SetOutput(output)
+	c.Flags().String("foo1", "", "required foo1")
+	c.MarkFlagRequired("foo1")
+	c.Flags().String("foo2", "", "required foo2")
+	c.MarkFlagRequired("foo2")
+	c.Flags().String("bar", "", "optional bar")
+
+	expected := fmt.Sprintf("Required flag(s) %q, %q have/has not been set", "foo1", "foo2")
+
+	if err := c.Execute(); err != nil {
+		if err.Error() != expected {
+			t.Errorf("expected %v, got %v", expected, err.Error())
+		}
+	}
+}
+
+func TestPersistentRequiredFlags(t *testing.T) {
+	parent := &Command{Use: "parent", Run: func(*Command, []string) {}}
+	output := new(bytes.Buffer)
+	parent.SetOutput(output)
+	parent.PersistentFlags().String("foo1", "", "required foo1")
+	parent.MarkPersistentFlagRequired("foo1")
+	parent.PersistentFlags().String("foo2", "", "required foo2")
+	parent.MarkPersistentFlagRequired("foo2")
+	parent.Flags().String("foo3", "", "optional foo3")
+
+	child := &Command{Use: "child", Run: func(*Command, []string) {}}
+	child.Flags().String("bar1", "", "required bar1")
+	child.MarkFlagRequired("bar1")
+	child.Flags().String("bar2", "", "required bar2")
+	child.MarkFlagRequired("bar2")
+	child.Flags().String("bar3", "", "optional bar3")
+
+	parent.AddCommand(child)
+	parent.SetArgs([]string{"child"})
+
+	expected := fmt.Sprintf("Required flag(s) %q, %q, %q, %q have/has not been set", "bar1", "bar2", "foo1", "foo2")
+
+	if err := parent.Execute(); err != nil {
+		if err.Error() != expected {
+			t.Errorf("expected %v, got %v", expected, err.Error())
+		}
+	}
+}