test(app): add tests for app module

systeroid/src/app.rs

@@ -227,3 +227,45 @@ impl<'a, Output: Write> App<'a, Output> {
         Ok(())
     }
 }
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use systeroid_core::config::Config;
+
+    #[test]
+    fn test_app() -> Result<()> {
+        let mut output = Vec::new();
+        let mut sysctl = Sysctl::init(Config {
+            no_pager: true,
+            ..Config::default()
+        })?;
+        let mut app = App::new(&mut sysctl, &mut output, false)?;
+
+        app.display_parameters(Regex::new("kernel|vm").ok(), false)?;
+        let result = String::from_utf8_lossy(&app.output);
+        assert!(result.contains("vm.zone_reclaim_mode ="));
+        assert!(result.contains("kernel.version ="));
+        app.output.clear();
+
+        app.tree_output = true;
+        app.display_parameters(None, true)?;
+        assert!(String::from_utf8_lossy(&app.output).contains("─ osrelease ="));
+        app.output.clear();
+
+        app.update_documentation(None)?;
+        app.display_documentation("kernel.acct")?;
+        assert!(String::from_utf8_lossy(&app.output).contains("highwater lowwater frequency"));
+        app.output.clear();
+
+        let param_name = String::from("kernel.version");
+        app.tree_output = false;
+        app.process_parameter(param_name.clone(), true, false)?;
+        let result = String::from_utf8_lossy(&app.output);
+        assert_eq!(1, result.lines().count());
+        assert!(result.contains(&param_name));
+        app.output.clear();
+
+        Ok(())
+    }
+}