Struct TestBackend

pub struct TestBackend { /* private fields */ }

A backend that can be used for tests.

When asserting equality, it is recommended to use TestBackend::assert_eq or assert_backend_snapshot instead of assert_eq.

Implementations

impl TestBackend

pub fn new(size: Size) -> Self

Creates a new TestBackend

pub fn new_with_layout(size: Size, layout: Layout) -> Self

Creates a new TestBackend with the cursor starting at the offsets given by the layout.

pub fn from_lines(lines: &[&str], size: Size) -> Self

Creates a new TestBackend from the lines. There must be <= size.height lines, and <= size.width chars per line.

It is not necessary to fill the lines so that it matches the dimensions of size exactly. Padding will be added to the end as required.

Panics

It panics if there are more than size.height lines or more than size.width chars per line.

pub fn reset_with_layout(&mut self, layout: Layout)

Clears all the cells and moves the cursor to the offsets given by the layout.

pub fn assert_eq(&self, other: &Self)

Asserts that two TestBackends are equal to each other, otherwise it panics printing what the backend would look like.

impl TestBackend

pub fn write_to_backend<B: Backend>(&self, backend: B) -> Result<()>

Writes all the cells of the TestBackend to the given backend.

A screenshot of what the printed output looks like:

pub fn write_to_buf<W: Write>(&self, buf: W) -> Result<()>

Available on crate features crossterm or termion only.

Writes all the cells of the TestBackend with the default backend (see get_backend).

A screenshot of what the printed output looks like:

Trait Implementations

impl Backend for TestBackend

fn enable_raw_mode(&mut self) -> Result<()>

Enables raw mode.

fn disable_raw_mode(&mut self) -> Result<()>

Disables raw mode.

fn hide_cursor(&mut self) -> Result<()>

Hides the cursor.

fn show_cursor(&mut self) -> Result<()>

Shows the cursor.

fn get_cursor_pos(&mut self) -> Result<(u16, u16)>

Gets the cursor position as (col, row). The top-left cell is (0, 0).

fn move_cursor_to(&mut self, x: u16, y: u16) -> Result<()>

Moves the cursor to given position. The top-left cell is (0, 0).

fn move_cursor(&mut self, direction: MoveDirection) -> Result<()>

Moves the cursor relative to the current position as per the direction.

fn scroll(&mut self, dist: i16) -> Result<()>

Scrolls the terminal the given number of rows.

fn set_attributes(&mut self, attributes: Attributes) -> Result<()>

Sets the given attributes removing ones which were previous applied.

fn set_fg(&mut self, color: Color) -> Result<()>

Sets the foreground color.

fn set_bg(&mut self, color: Color) -> Result<()>

Sets the background color.

fn clear(&mut self, clear_type: ClearType) -> Result<()>

Clears the cells given by clear_type

fn size(&self) -> Result<Size>

Gets the size of the terminal in rows and columns.

fn write_styled(&mut self, styled: &Styled<dyn Display + '_>) -> Result<()>

Write a styled object to the backend.

impl Clone for TestBackend

fn clone(&self) -> TestBackend

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for TestBackend

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.

impl Display for TestBackend

Available on crate features crossterm or termion only.

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Writes all the cells of the TestBackend using write_to_buf.

A screenshot of what the printed output looks like:

impl PartialEq for TestBackend

fn eq(&self, other: &Self) -> bool

Visual equality to another backend. This means that if the cells of both backends were rendered on a terminal, they would look the same. It however does not mean, that the hidden scrollback buffer is the same, or the current attributes are the same, or event the cursor position if it is hidden.

fn ne(&self, other: &Rhs) -> bool

Tests for !=. The default implementation is almost always sufficient, and should not be overridden without very good reason.

impl Write for TestBackend

fn write(&mut self, buf: &[u8]) -> Result<usize>

Writes a buffer into this writer, returning how many bytes were written.

fn flush(&mut self) -> Result<()>

Flushes this output stream, ensuring that all intermediately buffered contents reach their destination.

fn write_vectored(&mut self, bufs: &[IoSlice<'_>]) -> Result<usize, Error>

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

fn is_write_vectored(&self) -> bool

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

Determines if this Writer has an efficient write_vectored implementation.

fn write_all(&mut self, buf: &[u8]) -> Result<(), Error>

Attempts to write an entire buffer into this writer.

fn write_all_vectored(&mut self, bufs: &mut [IoSlice<'_>]) -> Result<(), Error>

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

Attempts to write multiple buffers into this writer.

fn write_fmt(&mut self, args: Arguments<'_>) -> Result<(), Error>

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

fn by_ref(&mut self) -> &mut Self

where Self: Sized,

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

impl Eq for TestBackend