tests: add some basic tests for rendering outputs

src/lib.rs

@@ -56,3 +56,74 @@ pub fn render_cli_error(err: &CliError, pretty: bool) -> String {
   render_error(err, pretty)
     .unwrap_or_else(|_| "{\"error\":{\"code\":1,\"message\":\"Unexpected error.\"}}".to_string())
 }
+
+#[cfg(test)]
+mod tests {
+  use super::*;
+
+  #[test]
+  fn parse_cli_from_when_called_with_valid_program_name_it_should_return_cli() {
+    let result = parse_cli_from(["test"]);
+
+    assert_eq!(
+      result,
+      Ok(Cli {
+        api_key: None,
+        base_url: None,
+        pretty: false
+      })
+    );
+  }
+
+  #[test]
+  fn parse_cli_from_when_called_with_unknown_flag_it_should_return_usage_error() {
+    let result = parse_cli_from(["test", "--bogus"]);
+
+    assert!(result.is_err());
+    assert_eq!(result.as_ref().unwrap_err().code, 2);
+    assert!(
+      result
+        .as_ref()
+        .unwrap_err()
+        .message
+        .contains("unexpected argument")
+    );
+  }
+
+  #[test]
+  fn parse_cli_from_when_called_with_help_flag_it_should_return_info_with_code_0() {
+    let result = parse_cli_from(["test", "--help"]);
+
+    let err = result.unwrap_err();
+
+    assert_eq!(err.code, 0);
+    assert!(err.message.contains(env!("CARGO_PKG_DESCRIPTION")));
+  }
+
+  #[test]
+  fn parse_cli_from_when_called_with_version_flag_it_should_return_info_with_code_0() {
+    let result = parse_cli_from(["test", "--version"]);
+
+    let err = result.unwrap_err();
+
+    assert_eq!(err.code, 0);
+    assert!(err.message.contains(env!("CARGO_PKG_NAME")));
+    assert!(err.message.contains(env!("CARGO_PKG_VERSION")));
+  }
+
+  #[test]
+  fn render_cli_error_when_called_with_error_it_should_render_json() {
+    let error = CliError {
+      code: 1,
+      message: String::from("Something went wrong"),
+    };
+
+    let result = render_cli_error(&error, false);
+
+    assert_eq!(
+      result,
+      r#"{"error":{"code":1,"message":"Something went wrong"}}"#
+    );
+  }
+}
+