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use std::{borrow::Cow, cell::RefCell, env, io};
use log::{LevelFilter, Log, Metadata, Record, SetLoggerError};
use crate::filter;
use crate::filter::Filter;
use crate::fmt;
use crate::fmt::writer::{self, Writer};
use crate::fmt::{FormatFn, Formatter};
/// The default name for the environment variable to read filters from.
pub const DEFAULT_FILTER_ENV: &str = "RUST_LOG";
/// The default name for the environment variable to read style preferences from.
pub const DEFAULT_WRITE_STYLE_ENV: &str = "RUST_LOG_STYLE";
/// `Builder` acts as builder for initializing a `Logger`.
///
/// It can be used to customize the log format, change the environment variable used
/// to provide the logging directives and also set the default log level filter.
///
/// # Examples
///
/// ```
/// # use std::io::Write;
/// use env_logger::Builder;
/// use log::{LevelFilter, error, info};
///
/// let mut builder = Builder::from_default_env();
///
/// builder
/// .format(|buf, record| writeln!(buf, "{} - {}", record.level(), record.args()))
/// .filter(None, LevelFilter::Info)
/// .init();
///
/// error!("error message");
/// info!("info message");
/// ```
#[derive(Default)]
pub struct Builder {
filter: filter::Builder,
writer: writer::Builder,
format: fmt::Builder,
built: bool,
}
impl Builder {
/// Initializes the log builder with defaults.
///
/// **NOTE:** This method won't read from any environment variables.
/// Use the [`filter`] and [`write_style`] methods to configure the builder
/// or use [`from_env`] or [`from_default_env`] instead.
///
/// # Examples
///
/// Create a new builder and configure filters and style:
///
/// ```
/// use log::LevelFilter;
/// use env_logger::{Builder, WriteStyle};
///
/// let mut builder = Builder::new();
///
/// builder
/// .filter(None, LevelFilter::Info)
/// .write_style(WriteStyle::Always)
/// .init();
/// ```
///
/// [`filter`]: #method.filter
/// [`write_style`]: #method.write_style
/// [`from_env`]: #method.from_env
/// [`from_default_env`]: #method.from_default_env
pub fn new() -> Builder {
Default::default()
}
/// Initializes the log builder from the environment.
///
/// The variables used to read configuration from can be tweaked before
/// passing in.
///
/// # Examples
///
/// Initialise a logger reading the log filter from an environment variable
/// called `MY_LOG`:
///
/// ```
/// use env_logger::Builder;
///
/// let mut builder = Builder::from_env("MY_LOG");
/// builder.init();
/// ```
///
/// Initialise a logger using the `MY_LOG` variable for filtering and
/// `MY_LOG_STYLE` for whether or not to write styles:
///
/// ```
/// use env_logger::{Builder, Env};
///
/// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE");
///
/// let mut builder = Builder::from_env(env);
/// builder.init();
/// ```
pub fn from_env<'a, E>(env: E) -> Self
where
E: Into<Env<'a>>,
{
let mut builder = Builder::new();
builder.parse_env(env);
builder
}
/// Applies the configuration from the environment.
///
/// This function allows a builder to be configured with default parameters,
/// to be then overridden by the environment.
///
/// # Examples
///
/// Initialise a logger with filter level `Off`, then override the log
/// filter from an environment variable called `MY_LOG`:
///
/// ```
/// use log::LevelFilter;
/// use env_logger::Builder;
///
/// let mut builder = Builder::new();
///
/// builder.filter_level(LevelFilter::Off);
/// builder.parse_env("MY_LOG");
/// builder.init();
/// ```
///
/// Initialise a logger with filter level `Off`, then use the `MY_LOG`
/// variable to override filtering and `MY_LOG_STYLE` to override whether
/// or not to write styles:
///
/// ```
/// use log::LevelFilter;
/// use env_logger::{Builder, Env};
///
/// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE");
///
/// let mut builder = Builder::new();
/// builder.filter_level(LevelFilter::Off);
/// builder.parse_env(env);
/// builder.init();
/// ```
pub fn parse_env<'a, E>(&mut self, env: E) -> &mut Self
where
E: Into<Env<'a>>,
{
let env = env.into();
if let Some(s) = env.get_filter() {
self.parse_filters(&s);
}
if let Some(s) = env.get_write_style() {
self.parse_write_style(&s);
}
self
}
/// Initializes the log builder from the environment using default variable names.
///
/// This method is a convenient way to call `from_env(Env::default())` without
/// having to use the `Env` type explicitly. The builder will use the
/// [default environment variables].
///
/// # Examples
///
/// Initialise a logger using the default environment variables:
///
/// ```
/// use env_logger::Builder;
///
/// let mut builder = Builder::from_default_env();
/// builder.init();
/// ```
///
/// [default environment variables]: struct.Env.html#default-environment-variables
pub fn from_default_env() -> Self {
Self::from_env(Env::default())
}
/// Applies the configuration from the environment using default variable names.
///
/// This method is a convenient way to call `parse_env(Env::default())` without
/// having to use the `Env` type explicitly. The builder will use the
/// [default environment variables].
///
/// # Examples
///
/// Initialise a logger with filter level `Off`, then configure it using the
/// default environment variables:
///
/// ```
/// use log::LevelFilter;
/// use env_logger::Builder;
///
/// let mut builder = Builder::new();
/// builder.filter_level(LevelFilter::Off);
/// builder.parse_default_env();
/// builder.init();
/// ```
///
/// [default environment variables]: struct.Env.html#default-environment-variables
pub fn parse_default_env(&mut self) -> &mut Self {
self.parse_env(Env::default())
}
/// Sets the format function for formatting the log output.
///
/// This function is called on each record logged and should format the
/// log record and output it to the given [`Formatter`].
///
/// The format function is expected to output the string directly to the
/// `Formatter` so that implementations can use the [`std::fmt`] macros
/// to format and output without intermediate heap allocations. The default
/// `env_logger` formatter takes advantage of this.
///
/// # Examples
///
/// Use a custom format to write only the log message:
///
/// ```
/// use std::io::Write;
/// use env_logger::Builder;
///
/// let mut builder = Builder::new();
///
/// builder.format(|buf, record| writeln!(buf, "{}", record.args()));
/// ```
///
/// [`Formatter`]: fmt/struct.Formatter.html
/// [`String`]: https://doc.rust-lang.org/stable/std/string/struct.String.html
/// [`std::fmt`]: https://doc.rust-lang.org/std/fmt/index.html
pub fn format<F: 'static>(&mut self, format: F) -> &mut Self
where
F: Fn(&mut Formatter, &Record) -> io::Result<()> + Sync + Send,
{
self.format.custom_format = Some(Box::new(format));
self
}
/// Use the default format.
///
/// This method will clear any custom format set on the builder.
pub fn default_format(&mut self) -> &mut Self {
self.format = Default::default();
self
}
/// Whether or not to write the level in the default format.
pub fn format_level(&mut self, write: bool) -> &mut Self {
self.format.format_level = write;
self
}
/// Whether or not to write the module path in the default format.
pub fn format_module_path(&mut self, write: bool) -> &mut Self {
self.format.format_module_path = write;
self
}
/// Whether or not to write the target in the default format.
pub fn format_target(&mut self, write: bool) -> &mut Self {
self.format.format_target = write;
self
}
/// Configures the amount of spaces to use to indent multiline log records.
/// A value of `None` disables any kind of indentation.
pub fn format_indent(&mut self, indent: Option<usize>) -> &mut Self {
self.format.format_indent = indent;
self
}
/// Configures if timestamp should be included and in what precision.
pub fn format_timestamp(&mut self, timestamp: Option<fmt::TimestampPrecision>) -> &mut Self {
self.format.format_timestamp = timestamp;
self
}
/// Configures the timestamp to use second precision.
pub fn format_timestamp_secs(&mut self) -> &mut Self {
self.format_timestamp(Some(fmt::TimestampPrecision::Seconds))
}
/// Configures the timestamp to use millisecond precision.
pub fn format_timestamp_millis(&mut self) -> &mut Self {
self.format_timestamp(Some(fmt::TimestampPrecision::Millis))
}
/// Configures the timestamp to use microsecond precision.
pub fn format_timestamp_micros(&mut self) -> &mut Self {
self.format_timestamp(Some(fmt::TimestampPrecision::Micros))
}
/// Configures the timestamp to use nanosecond precision.
pub fn format_timestamp_nanos(&mut self) -> &mut Self {
self.format_timestamp(Some(fmt::TimestampPrecision::Nanos))
}
/// Configures the end of line suffix.
pub fn format_suffix(&mut self, suffix: &'static str) -> &mut Self {
self.format.format_suffix = suffix;
self
}
/// Adds a directive to the filter for a specific module.
///
/// # Examples
///
/// Only include messages for info and above for logs in `path::to::module`:
///
/// ```
/// use env_logger::Builder;
/// use log::LevelFilter;
///
/// let mut builder = Builder::new();
///
/// builder.filter_module("path::to::module", LevelFilter::Info);
/// ```
pub fn filter_module(&mut self, module: &str, level: LevelFilter) -> &mut Self {
self.filter.filter_module(module, level);
self
}
/// Adds a directive to the filter for all modules.
///
/// # Examples
///
/// Only include messages for info and above for logs globally:
///
/// ```
/// use env_logger::Builder;
/// use log::LevelFilter;
///
/// let mut builder = Builder::new();
///
/// builder.filter_level(LevelFilter::Info);
/// ```
pub fn filter_level(&mut self, level: LevelFilter) -> &mut Self {
self.filter.filter_level(level);
self
}
/// Adds filters to the logger.
///
/// The given module (if any) will log at most the specified level provided.
/// If no module is provided then the filter will apply to all log messages.
///
/// # Examples
///
/// Only include messages for info and above for logs in `path::to::module`:
///
/// ```
/// use env_logger::Builder;
/// use log::LevelFilter;
///
/// let mut builder = Builder::new();
///
/// builder.filter(Some("path::to::module"), LevelFilter::Info);
/// ```
pub fn filter(&mut self, module: Option<&str>, level: LevelFilter) -> &mut Self {
self.filter.filter(module, level);
self
}
/// Parses the directives string in the same form as the `RUST_LOG`
/// environment variable.
///
/// See the module documentation for more details.
pub fn parse_filters(&mut self, filters: &str) -> &mut Self {
self.filter.parse(filters);
self
}
/// Sets the target for the log output.
///
/// Env logger can log to either stdout, stderr or a custom pipe. The default is stderr.
///
/// The custom pipe can be used to send the log messages to a custom sink (for example a file).
/// Do note that direct writes to a file can become a bottleneck due to IO operation times.
///
/// # Examples
///
/// Write log message to `stdout`:
///
/// ```
/// use env_logger::{Builder, Target};
///
/// let mut builder = Builder::new();
///
/// builder.target(Target::Stdout);
/// ```
pub fn target(&mut self, target: fmt::Target) -> &mut Self {
self.writer.target(target);
self
}
/// Sets whether or not styles will be written.
///
/// This can be useful in environments that don't support control characters
/// for setting colors.
///
/// # Examples
///
/// Never attempt to write styles:
///
/// ```
/// use env_logger::{Builder, WriteStyle};
///
/// let mut builder = Builder::new();
///
/// builder.write_style(WriteStyle::Never);
/// ```
pub fn write_style(&mut self, write_style: fmt::WriteStyle) -> &mut Self {
self.writer.write_style(write_style);
self
}
/// Parses whether or not to write styles in the same form as the `RUST_LOG_STYLE`
/// environment variable.
///
/// See the module documentation for more details.
pub fn parse_write_style(&mut self, write_style: &str) -> &mut Self {
self.writer.parse_write_style(write_style);
self
}
/// Sets whether or not the logger will be used in unit tests.
///
/// If `is_test` is `true` then the logger will allow the testing framework to
/// capture log records rather than printing them to the terminal directly.
pub fn is_test(&mut self, is_test: bool) -> &mut Self {
self.writer.is_test(is_test);
self
}
/// Initializes the global logger with the built env logger.
///
/// This should be called early in the execution of a Rust program. Any log
/// events that occur before initialization will be ignored.
///
/// # Errors
///
/// This function will fail if it is called more than once, or if another
/// library has already initialized a global logger.
pub fn try_init(&mut self) -> Result<(), SetLoggerError> {
let logger = self.build();
let max_level = logger.filter();
let r = log::set_boxed_logger(Box::new(logger));
if r.is_ok() {
log::set_max_level(max_level);
}
r
}
/// Initializes the global logger with the built env logger.
///
/// This should be called early in the execution of a Rust program. Any log
/// events that occur before initialization will be ignored.
///
/// # Panics
///
/// This function will panic if it is called more than once, or if another
/// library has already initialized a global logger.
pub fn init(&mut self) {
self.try_init()
.expect("Builder::init should not be called after logger initialized");
}
/// Build an env logger.
///
/// The returned logger implements the `Log` trait and can be installed manually
/// or nested within another logger.
pub fn build(&mut self) -> Logger {
assert!(!self.built, "attempt to re-use consumed builder");
self.built = true;
Logger {
writer: self.writer.build(),
filter: self.filter.build(),
format: self.format.build(),
}
}
}
impl std::fmt::Debug for Builder {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
if self.built {
f.debug_struct("Logger").field("built", &true).finish()
} else {
f.debug_struct("Logger")
.field("filter", &self.filter)
.field("writer", &self.writer)
.finish()
}
}
}
/// The env logger.
///
/// This struct implements the `Log` trait from the [`log` crate][log-crate-url],
/// which allows it to act as a logger.
///
/// The [`init()`], [`try_init()`], [`Builder::init()`] and [`Builder::try_init()`]
/// methods will each construct a `Logger` and immediately initialize it as the
/// default global logger.
///
/// If you'd instead need access to the constructed `Logger`, you can use
/// the associated [`Builder`] and install it with the
/// [`log` crate][log-crate-url] directly.
///
/// [log-crate-url]: https://docs.rs/log
/// [`init()`]: fn.init.html
/// [`try_init()`]: fn.try_init.html
/// [`Builder::init()`]: struct.Builder.html#method.init
/// [`Builder::try_init()`]: struct.Builder.html#method.try_init
/// [`Builder`]: struct.Builder.html
pub struct Logger {
writer: Writer,
filter: Filter,
format: FormatFn,
}
impl Logger {
/// Creates the logger from the environment.
///
/// The variables used to read configuration from can be tweaked before
/// passing in.
///
/// # Examples
///
/// Create a logger reading the log filter from an environment variable
/// called `MY_LOG`:
///
/// ```
/// use env_logger::Logger;
///
/// let logger = Logger::from_env("MY_LOG");
/// ```
///
/// Create a logger using the `MY_LOG` variable for filtering and
/// `MY_LOG_STYLE` for whether or not to write styles:
///
/// ```
/// use env_logger::{Logger, Env};
///
/// let env = Env::new().filter_or("MY_LOG", "info").write_style_or("MY_LOG_STYLE", "always");
///
/// let logger = Logger::from_env(env);
/// ```
pub fn from_env<'a, E>(env: E) -> Self
where
E: Into<Env<'a>>,
{
Builder::from_env(env).build()
}
/// Creates the logger from the environment using default variable names.
///
/// This method is a convenient way to call `from_env(Env::default())` without
/// having to use the `Env` type explicitly. The logger will use the
/// [default environment variables].
///
/// # Examples
///
/// Creates a logger using the default environment variables:
///
/// ```
/// use env_logger::Logger;
///
/// let logger = Logger::from_default_env();
/// ```
///
/// [default environment variables]: struct.Env.html#default-environment-variables
pub fn from_default_env() -> Self {
Builder::from_default_env().build()
}
/// Returns the maximum `LevelFilter` that this env logger instance is
/// configured to output.
pub fn filter(&self) -> LevelFilter {
self.filter.filter()
}
/// Checks if this record matches the configured filter.
pub fn matches(&self, record: &Record) -> bool {
self.filter.matches(record)
}
}
impl Log for Logger {
fn enabled(&self, metadata: &Metadata) -> bool {
self.filter.enabled(metadata)
}
fn log(&self, record: &Record) {
if self.matches(record) {
// Log records are written to a thread-local buffer before being printed
// to the terminal. We clear these buffers afterwards, but they aren't shrunk
// so will always at least have capacity for the largest log record formatted
// on that thread.
//
// If multiple `Logger`s are used by the same threads then the thread-local
// formatter might have different color support. If this is the case the
// formatter and its buffer are discarded and recreated.
thread_local! {
static FORMATTER: RefCell<Option<Formatter>> = RefCell::new(None);
}
let print = |formatter: &mut Formatter, record: &Record| {
let _ =
(self.format)(formatter, record).and_then(|_| formatter.print(&self.writer));
// Always clear the buffer afterwards
formatter.clear();
};
let printed = FORMATTER
.try_with(|tl_buf| {
match tl_buf.try_borrow_mut() {
// There are no active borrows of the buffer
Ok(mut tl_buf) => match *tl_buf {
// We have a previously set formatter
Some(ref mut formatter) => {
// Check the buffer style. If it's different from the logger's
// style then drop the buffer and recreate it.
if formatter.write_style() != self.writer.write_style() {
*formatter = Formatter::new(&self.writer);
}
print(formatter, record);
}
// We don't have a previously set formatter
None => {
let mut formatter = Formatter::new(&self.writer);
print(&mut formatter, record);
*tl_buf = Some(formatter);
}
},
// There's already an active borrow of the buffer (due to re-entrancy)
Err(_) => {
print(&mut Formatter::new(&self.writer), record);
}
}
})
.is_ok();
if !printed {
// The thread-local storage was not available (because its
// destructor has already run). Create a new single-use
// Formatter on the stack for this call.
print(&mut Formatter::new(&self.writer), record);
}
}
}
fn flush(&self) {}
}
impl std::fmt::Debug for Logger {
fn fmt(&self, f: &mut std::fmt::Formatter) -> std::fmt::Result {
f.debug_struct("Logger")
.field("filter", &self.filter)
.finish()
}
}
/// Set of environment variables to configure from.
///
/// # Default environment variables
///
/// By default, the `Env` will read the following environment variables:
///
/// - `RUST_LOG`: the level filter
/// - `RUST_LOG_STYLE`: whether or not to print styles with records.
///
/// These sources can be configured using the builder methods on `Env`.
#[derive(Debug)]
pub struct Env<'a> {
filter: Var<'a>,
write_style: Var<'a>,
}
impl<'a> Env<'a> {
/// Get a default set of environment variables.
pub fn new() -> Self {
Self::default()
}
/// Specify an environment variable to read the filter from.
pub fn filter<E>(mut self, filter_env: E) -> Self
where
E: Into<Cow<'a, str>>,
{
self.filter = Var::new(filter_env);
self
}
/// Specify an environment variable to read the filter from.
///
/// If the variable is not set, the default value will be used.
pub fn filter_or<E, V>(mut self, filter_env: E, default: V) -> Self
where
E: Into<Cow<'a, str>>,
V: Into<Cow<'a, str>>,
{
self.filter = Var::new_with_default(filter_env, default);
self
}
/// Use the default environment variable to read the filter from.
///
/// If the variable is not set, the default value will be used.
pub fn default_filter_or<V>(mut self, default: V) -> Self
where
V: Into<Cow<'a, str>>,
{
self.filter = Var::new_with_default(DEFAULT_FILTER_ENV, default);
self
}
fn get_filter(&self) -> Option<String> {
self.filter.get()
}
/// Specify an environment variable to read the style from.
pub fn write_style<E>(mut self, write_style_env: E) -> Self
where
E: Into<Cow<'a, str>>,
{
self.write_style = Var::new(write_style_env);
self
}
/// Specify an environment variable to read the style from.
///
/// If the variable is not set, the default value will be used.
pub fn write_style_or<E, V>(mut self, write_style_env: E, default: V) -> Self
where
E: Into<Cow<'a, str>>,
V: Into<Cow<'a, str>>,
{
self.write_style = Var::new_with_default(write_style_env, default);
self
}
/// Use the default environment variable to read the style from.
///
/// If the variable is not set, the default value will be used.
pub fn default_write_style_or<V>(mut self, default: V) -> Self
where
V: Into<Cow<'a, str>>,
{
self.write_style = Var::new_with_default(DEFAULT_WRITE_STYLE_ENV, default);
self
}
fn get_write_style(&self) -> Option<String> {
self.write_style.get()
}
}
impl<'a, T> From<T> for Env<'a>
where
T: Into<Cow<'a, str>>,
{
fn from(filter_env: T) -> Self {
Env::default().filter(filter_env.into())
}
}
impl<'a> Default for Env<'a> {
fn default() -> Self {
Env {
filter: Var::new(DEFAULT_FILTER_ENV),
write_style: Var::new(DEFAULT_WRITE_STYLE_ENV),
}
}
}
#[derive(Debug)]
struct Var<'a> {
name: Cow<'a, str>,
default: Option<Cow<'a, str>>,
}
impl<'a> Var<'a> {
fn new<E>(name: E) -> Self
where
E: Into<Cow<'a, str>>,
{
Var {
name: name.into(),
default: None,
}
}
fn new_with_default<E, V>(name: E, default: V) -> Self
where
E: Into<Cow<'a, str>>,
V: Into<Cow<'a, str>>,
{
Var {
name: name.into(),
default: Some(default.into()),
}
}
fn get(&self) -> Option<String> {
env::var(&*self.name)
.ok()
.or_else(|| self.default.to_owned().map(|v| v.into_owned()))
}
}
/// Attempts to initialize the global logger with an env logger.
///
/// This should be called early in the execution of a Rust program. Any log
/// events that occur before initialization will be ignored.
///
/// # Errors
///
/// This function will fail if it is called more than once, or if another
/// library has already initialized a global logger.
pub fn try_init() -> Result<(), SetLoggerError> {
try_init_from_env(Env::default())
}
/// Initializes the global logger with an env logger.
///
/// This should be called early in the execution of a Rust program. Any log
/// events that occur before initialization will be ignored.
///
/// # Panics
///
/// This function will panic if it is called more than once, or if another
/// library has already initialized a global logger.
pub fn init() {
try_init().expect("env_logger::init should not be called after logger initialized");
}
/// Attempts to initialize the global logger with an env logger from the given
/// environment variables.
///
/// This should be called early in the execution of a Rust program. Any log
/// events that occur before initialization will be ignored.
///
/// # Examples
///
/// Initialise a logger using the `MY_LOG` environment variable for filters
/// and `MY_LOG_STYLE` for writing colors:
///
/// ```
/// use env_logger::{Builder, Env};
///
/// # fn run() -> Result<(), Box<dyn ::std::error::Error>> {
/// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE");
///
/// env_logger::try_init_from_env(env)?;
///
/// Ok(())
/// # }
/// # run().unwrap();
/// ```
///
/// # Errors
///
/// This function will fail if it is called more than once, or if another
/// library has already initialized a global logger.
pub fn try_init_from_env<'a, E>(env: E) -> Result<(), SetLoggerError>
where
E: Into<Env<'a>>,
{
let mut builder = Builder::from_env(env);
builder.try_init()
}
/// Initializes the global logger with an env logger from the given environment
/// variables.
///
/// This should be called early in the execution of a Rust program. Any log
/// events that occur before initialization will be ignored.
///
/// # Examples
///
/// Initialise a logger using the `MY_LOG` environment variable for filters
/// and `MY_LOG_STYLE` for writing colors:
///
/// ```
/// use env_logger::{Builder, Env};
///
/// let env = Env::new().filter("MY_LOG").write_style("MY_LOG_STYLE");
///
/// env_logger::init_from_env(env);
/// ```
///
/// # Panics
///
/// This function will panic if it is called more than once, or if another
/// library has already initialized a global logger.
pub fn init_from_env<'a, E>(env: E)
where
E: Into<Env<'a>>,
{
try_init_from_env(env)
.expect("env_logger::init_from_env should not be called after logger initialized");
}
/// Create a new builder with the default environment variables.
///
/// The builder can be configured before being initialized.
/// This is a convenient way of calling [`Builder::from_default_env`].
///
/// [`Builder::from_default_env`]: struct.Builder.html#method.from_default_env
pub fn builder() -> Builder {
Builder::from_default_env()
}
/// Create a builder from the given environment variables.
///
/// The builder can be configured before being initialized.
#[deprecated(
since = "0.8.0",
note = "Prefer `env_logger::Builder::from_env()` instead."
)]
pub fn from_env<'a, E>(env: E) -> Builder
where
E: Into<Env<'a>>,
{
Builder::from_env(env)
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn env_get_filter_reads_from_var_if_set() {
env::set_var("env_get_filter_reads_from_var_if_set", "from var");
let env = Env::new().filter_or("env_get_filter_reads_from_var_if_set", "from default");
assert_eq!(Some("from var".to_owned()), env.get_filter());
}
#[test]
fn env_get_filter_reads_from_default_if_var_not_set() {
env::remove_var("env_get_filter_reads_from_default_if_var_not_set");
let env = Env::new().filter_or(
"env_get_filter_reads_from_default_if_var_not_set",
"from default",
);
assert_eq!(Some("from default".to_owned()), env.get_filter());
}
#[test]
fn env_get_write_style_reads_from_var_if_set() {
env::set_var("env_get_write_style_reads_from_var_if_set", "from var");
let env =
Env::new().write_style_or("env_get_write_style_reads_from_var_if_set", "from default");
assert_eq!(Some("from var".to_owned()), env.get_write_style());
}
#[test]
fn env_get_write_style_reads_from_default_if_var_not_set() {
env::remove_var("env_get_write_style_reads_from_default_if_var_not_set");
let env = Env::new().write_style_or(
"env_get_write_style_reads_from_default_if_var_not_set",
"from default",
);
assert_eq!(Some("from default".to_owned()), env.get_write_style());
}
#[test]
fn builder_parse_env_overrides_existing_filters() {
env::set_var(
"builder_parse_default_env_overrides_existing_filters",
"debug",
);
let env = Env::new().filter("builder_parse_default_env_overrides_existing_filters");
let mut builder = Builder::new();
builder.filter_level(LevelFilter::Trace);
// Overrides global level to debug
builder.parse_env(env);
assert_eq!(builder.filter.build().filter(), LevelFilter::Debug);
}
}