nautilus_core/
env.rs

1// -------------------------------------------------------------------------------------------------
2//  Copyright (C) 2015-2025 Nautech Systems Pty Ltd. All rights reserved.
3//  https://nautechsystems.io
4//
5//  Licensed under the GNU Lesser General Public License Version 3.0 (the "License");
6//  You may not use this file except in compliance with the License.
7//  You may obtain a copy of the License at https://www.gnu.org/licenses/lgpl-3.0.en.html
8//
9//  Unless required by applicable law or agreed to in writing, software
10//  distributed under the License is distributed on an "AS IS" BASIS,
11//  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12//  See the License for the specific language governing permissions and
13//  limitations under the License.
14// -------------------------------------------------------------------------------------------------
15
16//! Cross-platform environment variable utilities.
17//!
18//! This module provides functions for safely accessing environment variables
19//! with proper error handling.
20
21/// Returns the value of the environment variable for the given `key`.
22///
23/// # Errors
24///
25/// Returns an error if the environment variable is not set.
26pub fn get_env_var(key: &str) -> anyhow::Result<String> {
27    match std::env::var(key) {
28        Ok(var) => Ok(var),
29        Err(_) => anyhow::bail!("environment variable '{key}' must be set"),
30    }
31}
32
33/// Returns the provided `value` if `Some`, otherwise falls back to reading
34/// the environment variable for the given `key`.
35///
36/// Only attempts to read the environment variable when `value` is `None`,
37/// avoiding unnecessary environment variable lookups and errors.
38///
39/// # Errors
40///
41/// Returns an error if `value` is `None` and the environment variable is not set.
42pub fn get_or_env_var(value: Option<String>, key: &str) -> anyhow::Result<String> {
43    match value {
44        Some(v) => Ok(v),
45        None => get_env_var(key),
46    }
47}
48
49////////////////////////////////////////////////////////////////////////////////
50// Tests
51////////////////////////////////////////////////////////////////////////////////
52
53#[cfg(test)]
54mod tests {
55    use rstest::*;
56
57    use super::*;
58
59    #[rstest]
60    fn test_get_env_var_success() {
61        // Test with a commonly available environment variable
62        if let Ok(path) = std::env::var("PATH") {
63            let result = get_env_var("PATH");
64            assert!(result.is_ok());
65            assert_eq!(result.unwrap(), path);
66        }
67    }
68
69    #[rstest]
70    fn test_get_env_var_not_set() {
71        // Use a highly unlikely environment variable name
72        let result = get_env_var("NONEXISTENT_ENV_VAR_THAT_SHOULD_NOT_EXIST_12345");
73        assert!(result.is_err());
74        assert!(result.unwrap_err().to_string().contains(
75            "environment variable 'NONEXISTENT_ENV_VAR_THAT_SHOULD_NOT_EXIST_12345' must be set"
76        ));
77    }
78
79    #[rstest]
80    fn test_get_env_var_error_message_format() {
81        let var_name = "DEFINITELY_NONEXISTENT_VAR_123456789";
82        let result = get_env_var(var_name);
83        assert!(result.is_err());
84        let error_msg = result.unwrap_err().to_string();
85        assert!(error_msg.contains(var_name));
86        assert!(error_msg.contains("must be set"));
87    }
88
89    #[rstest]
90    fn test_get_or_env_var_with_some_value() {
91        let provided_value = Some("provided_value".to_string());
92        let result = get_or_env_var(provided_value, "PATH");
93        assert!(result.is_ok());
94        assert_eq!(result.unwrap(), "provided_value");
95    }
96
97    #[rstest]
98    fn test_get_or_env_var_with_none_and_env_var_set() {
99        // Test with a commonly available environment variable
100        if let Ok(path) = std::env::var("PATH") {
101            let result = get_or_env_var(None, "PATH");
102            assert!(result.is_ok());
103            assert_eq!(result.unwrap(), path);
104        }
105    }
106
107    #[rstest]
108    fn test_get_or_env_var_with_none_and_env_var_not_set() {
109        let result = get_or_env_var(None, "NONEXISTENT_ENV_VAR_THAT_SHOULD_NOT_EXIST_67890");
110        assert!(result.is_err());
111        assert!(result.unwrap_err().to_string().contains(
112            "environment variable 'NONEXISTENT_ENV_VAR_THAT_SHOULD_NOT_EXIST_67890' must be set"
113        ));
114    }
115
116    #[rstest]
117    fn test_get_or_env_var_empty_string_value() {
118        // Empty string is still a valid value that should be returned
119        let provided_value = Some(String::new());
120        let result = get_or_env_var(provided_value, "PATH");
121        assert!(result.is_ok());
122        assert_eq!(result.unwrap(), "");
123    }
124
125    #[rstest]
126    fn test_get_or_env_var_priority() {
127        // When both value and env var are available, value takes precedence
128        // Using PATH as it should be available in most environments
129        if std::env::var("PATH").is_ok() {
130            let provided = Some("custom_value_takes_priority".to_string());
131            let result = get_or_env_var(provided, "PATH");
132            assert!(result.is_ok());
133            assert_eq!(result.unwrap(), "custom_value_takes_priority");
134        }
135    }
136}
nautilus_core/env.rs

nautilus_core/
env.rs
