diff --git a/.gitignore b/.gitignore new file mode 100644 index 0000000..96ef6c0 --- /dev/null +++ b/.gitignore @@ -0,0 +1,2 @@ +/target +Cargo.lock diff --git a/Cargo.toml b/Cargo.toml new file mode 100644 index 0000000..fadb8b3 --- /dev/null +++ b/Cargo.toml @@ -0,0 +1,13 @@ +[package] +name = "temp-env" +version = "0.1.0" +authors = ["Volker Mische ", "Fabian Braun "] +license = "MIT OR Apache-2.0" +repository = "https://github.com/vmx/temp-env" +description = "Set environment variables temporarily." +keywords = ["env", "environment", "envvar", "temporary", "testing"] +categories = ["development-tools", "development-tools::testing"] +edition = "2018" + +[dependencies] +once_cell = "1.8.0" diff --git a/LICENSE-APACHE b/LICENSE-APACHE new file mode 100644 index 0000000..f8e5e5e --- /dev/null +++ b/LICENSE-APACHE @@ -0,0 +1,201 @@ + Apache License + Version 2.0, January 2004 + http://www.apache.org/licenses/ + +TERMS AND CONDITIONS FOR USE, REPRODUCTION, AND DISTRIBUTION + +1. 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IN NO EVENT SHALL THE +AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER +LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, +OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN +THE SOFTWARE. diff --git a/README.md b/README.md new file mode 100644 index 0000000..797e5f8 --- /dev/null +++ b/README.md @@ -0,0 +1,60 @@ +temp-env +======== + +Set environment variables temporarily. + +This crate is useful for testing with different environment variables that should not interfere. + +This code started as a small test helper written by [@fabian-braun] and [@nbaztec] and published by [@fabian-braun] +on [StackOverflow]. [@vmx] found it useful and took the time to make it a proper crate. + +Example +------- + +```rust +temp_env::with_var("MY_ENV_VAR", Some("production"), || { + // Run some code where `MY_ENV_VAR` set to `"production"`. +}); + + +temp_env::with_vars( + vec![ + ("FIRST_VAR", Some("Hello")), + ("SECOND_VAR", Some("World!")), + ], + || { + // Run some code where `FIRST_VAR` is set to `"Hello"` and `SECOND_VAR` is set to + // `"World!"`. + } +); + +temp_env::with_vars( + vec![ + ("FIRST_VAR", Some("Hello")), + ("SECOND_VAR", None), + ], + || { + // Run some code where `FIRST_VAR` is set to `"Hello"` and `SECOND_VAR` is unset (even if + // it was set before) + } +); +``` + + +License +------- + +This project is licensed under either of + + * Apache License, Version 2.0, ([LICENSE-APACHE]) or https://www.apache.org/licenses/LICENSE-2.0) + * MIT license ([LICENSE-MIT] or https://opensource.org/licenses/MIT) + +at your option. + + +[StackOverflow]: https://stackoverflow.com/questions/35858323/how-can-i-test-rust-methods-that-depend-on-environment-variables/67433684#67433684 +[@fabian-braun]: https://github.com/fabian-braun +[@nbaztec]: https://github.com/nbaztec +[@vmx]: https://github.com/vmx +[LICENSE-APACHE]: LICENSE-APACHE +[LICENSE-MIT]: LICENSE-MIT diff --git a/src/lib.rs b/src/lib.rs new file mode 100644 index 0000000..2cdcf18 --- /dev/null +++ b/src/lib.rs @@ -0,0 +1,368 @@ +#![deny(missing_docs)] +//! This crate is for setting environment variables temporarily. +//! +//! It is useful for testing with different environment variables that should not interfere. +//! +//! # Examples +//! +//! ```rust +//! temp_env::with_var("MY_ENV_VAR", Some("production"), || { +//! // Run some code where `MY_ENV_VAR` set to `"production"`. +//! }); +//! +//! +//! temp_env::with_vars( +//! vec![ +//! ("FIRST_VAR", Some("Hello")), +//! ("SECOND_VAR", Some("World!")), +//! ], +//! || { +//! // Run some code where `FIRST_VAR` is set to `"Hello"` and `SECOND_VAR` is set to +//! // `"World!"`. +//! } +//! ); +//! +//! temp_env::with_vars( +//! vec![ +//! ("FIRST_VAR", Some("Hello")), +//! ("SECOND_VAR", None), +//! ], +//! || { +//! // Run some code where `FIRST_VAR` is set to `"Hello"` and `SECOND_VAR` is unset (even if +//! // it was set before) +//! } +//! ); + +use std::collections::HashMap; +use std::env; +use std::ffi::OsStr; +use std::hash::Hash; +use std::panic::{self, RefUnwindSafe, UnwindSafe}; +use std::sync::Mutex; + +use once_cell::sync::Lazy; + +/// Make sure that the environment isn't modified concurrently. +static SERIAL_TEST: Lazy> = Lazy::new(Default::default); + +/// Sets a single environment variable for the duration of the closure. +/// +/// The previous values are restored when the closure completes or panics, before unwinding the +/// panic. +/// +/// If `value` is set to `None`, then the environment variable is unset. +pub fn with_var(key: K, value: Option, closure: F) +where + K: AsRef + Clone + Eq + Hash, + V: AsRef + Clone, + F: Fn() + UnwindSafe + RefUnwindSafe, +{ + with_vars(vec![(key, value)], closure) +} + +/// Sets environment variables for the duration of the closure. +/// +/// The previous values are restored when the closure completes or panics, before unwinding the +/// panic. +/// +/// If a `value` is set to `None`, then the environment variable is unset. +/// +/// If the variable with the same name is set multiple times, the last one wins. +pub fn with_vars(kvs: Vec<(K, Option)>, closure: F) +where + K: AsRef + Clone + Eq + Hash, + V: AsRef + Clone, + F: Fn() + UnwindSafe + RefUnwindSafe, +{ + let guard = SERIAL_TEST.lock().unwrap(); + let mut old_kvs: HashMap> = HashMap::new(); + for (key, value) in kvs { + // If the same key is given several times, the original/old value is only correct before + // the environment was updated. + if !old_kvs.contains_key(&key) { + let old_value = env::var(&key).ok(); + old_kvs.insert(key.clone(), old_value); + } + update_env(&key, value); + } + + match panic::catch_unwind(|| { + closure(); + }) { + Ok(_) => { + for (key, value) in old_kvs { + update_env(key, value); + } + } + Err(err) => { + for (key, value) in old_kvs { + update_env(key, value); + } + drop(guard); + panic::resume_unwind(err); + } + }; +} + +fn update_env(key: K, value: Option) +where + K: AsRef, + V: AsRef, +{ + match value { + Some(v) => env::set_var(key, v), + None => env::remove_var(key), + } +} + +// Make sure that all tests use independent environment variables, so that they don't interfere if +// run in parallel. +#[cfg(test)] +mod tests { + use std::{env, panic}; + + /// Test whether setting a variable is correctly undone. + #[test] + fn test_with_var_set() { + let hello_not_set = env::var("HELLO"); + assert!(hello_not_set.is_err(), "`HELLO` must not be set."); + + crate::with_var("HELLO", Some("world!"), || { + let hello_is_set = env::var("HELLO").unwrap(); + assert_eq!(hello_is_set, "world!", "`HELLO` must be set to \"world!\"."); + }); + + let hello_not_set_after = env::var("HELLO"); + assert!(hello_not_set_after.is_err(), "`HELLO` must not be set."); + } + + /// Test whether unsetting a variable is correctly undone. + #[test] + fn test_with_var_unset() { + env::set_var("FOO", "bar"); + let foo_is_set = env::var("FOO").unwrap(); + assert_eq!(foo_is_set, "bar", "`FOO` must be set to \"bar\"."); + + crate::with_var("FOO", None::<&str>, || { + let foo_not_set = env::var("FOO"); + assert!(foo_not_set.is_err(), "`FOO` must not be set."); + }); + + let foo_is_set_after = env::var("FOO").unwrap(); + assert_eq!(foo_is_set_after, "bar", "`FOO` must be set to \"bar\"."); + } + + /// Test whether overriding an existing variable is correctly undone. + #[test] + fn test_with_var_override() { + env::set_var("BLAH", "blub"); + let blah_is_set = env::var("BLAH").unwrap(); + assert_eq!(blah_is_set, "blub", "`BLAH` must be set to \"blah\"."); + + crate::with_var("BLAH", Some("new"), || { + let blah_is_set_new = env::var("BLAH").unwrap(); + assert_eq!(blah_is_set_new, "new", "`BLAH` must be set to \"newb\"."); + }); + + let blah_is_set_after = env::var("BLAH").unwrap(); + assert_eq!( + blah_is_set_after, "blub", + "`BLAH` must be set to \"blubr\"." + ); + } + + /// Test whether overriding a variable is correctly undone in case of a panic. + #[test] + fn test_with_var_panic() { + env::set_var("PANIC", "panic"); + let panic_is_set = env::var("PANIC").unwrap(); + assert_eq!(panic_is_set, "panic", "`PANIC` must be set to \"panic\"."); + + let did_panic = panic::catch_unwind(|| { + crate::with_var("PANIC", Some("don't panic"), || { + let panic_is_set_new = env::var("PANIC").unwrap(); + assert_eq!( + panic_is_set_new, "don't panic", + "`PANIC` must be set to \"don't panic\"." + ); + panic!("abort this closure with a panic."); + }); + }); + + assert!(did_panic.is_err(), "The closure must panic."); + let panic_is_set_after = env::var("PANIC").unwrap(); + assert_eq!( + panic_is_set_after, "panic", + "`PANIC` must be set to \"panic\"." + ); + } + + /// Test whether setting multiple variable is correctly undone. + #[test] + fn test_with_vars_set() { + let one_not_set = env::var("ONE"); + assert!(one_not_set.is_err(), "`ONE` must not be set."); + let two_not_set = env::var("TWO"); + assert!(two_not_set.is_err(), "`TWO` must not be set."); + + crate::with_vars(vec![("ONE", Some("1")), ("TWO", Some("2"))], || { + let one_is_set = env::var("ONE").unwrap(); + assert_eq!(one_is_set, "1", "`ONE` must be set to \"1\"."); + let two_is_set = env::var("TWO").unwrap(); + assert_eq!(two_is_set, "2", "`TWO` must be set to \"2\"."); + }); + + let one_not_set_after = env::var("ONE"); + assert!(one_not_set_after.is_err(), "`ONE` must not be set."); + let two_not_set_after = env::var("TWO"); + assert!(two_not_set_after.is_err(), "`TWO` must not be set."); + } + + /// Test whether unsetting one of the variable is correctly undone. + #[test] + fn test_with_vars_unset() { + let to_be_set_not_set = env::var("TO_BE_SET"); + assert!(to_be_set_not_set.is_err(), "`TO_BE_SET` must not be set."); + env::set_var("TO_BE_UNSET", "unset"); + let to_be_unset_is_set = env::var("TO_BE_UNSET").unwrap(); + assert_eq!( + to_be_unset_is_set, "unset", + "`TO_BE_UNSET` must be set to \"unset\"." + ); + + crate::with_vars( + vec![("TO_BE_SET", Some("set")), ("TO_BE_UNSET", None::<&str>)], + || { + let to_be_set_is_set = env::var("TO_BE_SET").unwrap(); + assert_eq!( + to_be_set_is_set, "set", + "`TO_BE_SET` must be set to \"set\"." + ); + let to_be_unset_not_set = env::var("TO_BE_UNSET"); + assert!( + to_be_unset_not_set.is_err(), + "`TO_BE_UNSET` must not be set." + ); + }, + ); + + let to_be_set_not_set_after = env::var("TO_BE_SET"); + assert!( + to_be_set_not_set_after.is_err(), + "`TO_BE_SET` must not be set." + ); + let to_be_unset_is_set_after = env::var("TO_BE_UNSET").unwrap(); + assert_eq!( + to_be_unset_is_set_after, "unset", + "`TO_BE_UNSET` must be set to \"unset\"." + ); + } + + /// Test whether overriding existing variables is correctly undone. + #[test] + fn test_with_vars_override() { + env::set_var("DOIT", "doit"); + let doit_is_set = env::var("DOIT").unwrap(); + assert_eq!(doit_is_set, "doit", "`DOIT` must be set to \"doit\"."); + env::set_var("NOW", "now"); + let now_is_set = env::var("NOW").unwrap(); + assert_eq!(now_is_set, "now", "`NOW` must be set to \"now\"."); + + crate::with_vars( + vec![("DOIT", Some("other")), ("NOW", Some("value"))], + || { + let doit_is_set_new = env::var("DOIT").unwrap(); + assert_eq!(doit_is_set_new, "other", "`DOIT` must be set to \"other\"."); + let now_is_set_new = env::var("NOW").unwrap(); + assert_eq!(now_is_set_new, "value", "`NOW` must be set to \"value\"."); + }, + ); + + let doit_is_set_after = env::var("DOIT").unwrap(); + assert_eq!(doit_is_set_after, "doit", "`DOIT` must be set to \"doit\"."); + let now_is_set_after = env::var("NOW").unwrap(); + assert_eq!(now_is_set_after, "now", "`NOW` must be set to \"now\"."); + } + + /// Test that setting the same variables twice, the latter one is used. + #[test] + fn test_with_vars_same_vars() { + let override_not_set = env::var("OVERRIDE"); + assert!(override_not_set.is_err(), "`OVERRIDE` must not be set."); + + crate::with_vars( + vec![ + ("OVERRIDE", Some("initial")), + ("OVERRIDE", Some("override")), + ], + || { + let override_is_set = env::var("OVERRIDE").unwrap(); + assert_eq!( + override_is_set, "override", + "`OVERRIDE` must be set to \"override\"." + ); + }, + ); + + let override_not_set_after = env::var("OVERRIDE"); + assert!( + override_not_set_after.is_err(), + "`OVERRIDE` must not be set." + ); + } + + /// Test that unsetting and setting the same variable leads to the variable being set. + #[test] + fn test_with_vars_unset_set() { + env::set_var("MY_VAR", "my_var"); + let my_var_is_set = env::var("MY_VAR").unwrap(); + assert_eq!( + my_var_is_set, "my_var", + "`MY_VAR` must be set to \"my_var`\"." + ); + + crate::with_vars( + vec![("MY_VAR", None::<&str>), ("MY_VAR", Some("new value"))], + || { + let my_var_is_set_new = env::var("MY_VAR").unwrap(); + assert_eq!( + my_var_is_set_new, "new value", + "`MY_VAR` must be set to \"new value\"." + ); + }, + ); + + let my_var_is_set_after = env::var("MY_VAR").unwrap(); + assert_eq!( + my_var_is_set_after, "my_var", + "`MY_VAR` must be set to \"my_var\"." + ); + } + + /// Test that setting and unsetting the same variable leads to the variable being unset. + #[test] + fn test_with_vars_set_unset() { + let not_my_var_not_set = env::var("NOT_MY_VAR"); + assert!(not_my_var_not_set.is_err(), "`NOT_MY_VAR` must not be set."); + + crate::with_vars( + vec![ + ("NOT_MY_VAR", Some("it is set")), + ("NOT_MY_VAR", None::<&str>), + ], + || { + let not_my_var_not_set_new = env::var("NOT_MY_VAR"); + assert!( + not_my_var_not_set_new.is_err(), + "`NOT_MY_VAR` must not be set." + ); + }, + ); + + let not_my_var_not_set_after = env::var("NOT_MY_VAR"); + assert!( + not_my_var_not_set_after.is_err(), + "`NOT_MY_VAR` must not be set." + ); + } +}