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pub struct TestWriter { /* private fields */ }
Expand description

A writer intended to support libtest’s output capturing for use in unit tests.

TestWriter is used by fmt::Subscriber or fmt::Layer to enable capturing support.

cargo test can only capture output from the standard library’s print! macro. See libtest’s output capturing for more details about output capturing.

Writing to io::stdout and io::stderr produces the same results as using libtest’s --nocapture option which may make the results look unreadable.

Implementations

Returns a new TestWriter with the default configuration.

Trait Implementations

Formats the value using the given formatter. Read more

Returns the “default value” for a type. Read more

The concrete io::Write implementation returned by make_writer. Read more

Returns an instance of Writer. Read more

Returns a Writer for writing data from the span or event described by the provided Metadata. Read more

Write a buffer into this writer, returning how many bytes were written. Read more

Flush this output stream, ensuring that all intermediately buffered contents reach their destination. Read more

Like write, except that it writes from a slice of buffers. Read more

🔬 This is a nightly-only experimental API. (can_vector #69941)

Determines if this Writer has an efficient write_vectored implementation. Read more

Attempts to write an entire buffer into this writer. Read more

🔬 This is a nightly-only experimental API. (write_all_vectored #70436)

Attempts to write multiple buffers into this writer. Read more

Writes a formatted string into this writer, returning any error encountered. Read more

Creates a “by reference” adapter for this instance of Write. Read more

Auto Trait Implementations

Blanket Implementations

Gets the TypeId of self. Read more

Immutably borrows from an owned value. Read more

Mutably borrows from an owned value. Read more

Returns the argument unchanged.

Calls U::from(self).

That is, this conversion is whatever the implementation of From<T> for U chooses to do.

Wraps self and returns a MakeWriter that will only write output for events at or below the provided verbosity Level. For instance, Level::TRACE is considered to be _more verbosethanLevel::INFO`. Read more

Wraps self and returns a MakeWriter that will only write output for events at or above the provided verbosity Level. Read more

Wraps self with a predicate that takes a span or event’s Metadata and returns a bool. The returned MakeWriter’s MakeWriter::make_writer_for method will check the predicate to determine if a writer should be produced for a given span or event. Read more

Combines self with another type implementing MakeWriter, returning a new MakeWriter that produces writers that write to both outputs. Read more

Combines self with another type implementing MakeWriter, returning a new MakeWriter that calls other’s make_writer if self’s make_writer returns OptionalWriter::none. Read more

The type returned in the event of a conversion error.

Performs the conversion.

The type returned in the event of a conversion error.

Performs the conversion.