Struct Description

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pub struct Description { /* private fields */ }

Expand description

A structured description, either of a (composed) matcher or of an assertion failure.

One can compose blocks of text into a Description. Each one appears on a new line. For example:

let description = Description::new()
    .text("A block")
    .text("Another block");
verify_that!(description, displays_as(eq("A block\nAnother block")))

One can embed nested descriptions into a Description. The resulting nested description is then rendered with an additional level of indentation. For example:

let inner_description = Description::new()
    .text("A block")
    .text("Another block");
let outer_description = Description::new()
    .text("Header")
    .nested(inner_description);
verify_that!(outer_description, displays_as(eq("\
Header
  A block
  Another block")))

One can also enumerate or bullet list the elements of a Description:

let description = Description::new()
    .text("First item")
    .text("Second item")
    .bullet_list();
verify_that!(description, displays_as(eq("\
* First item
* Second item")))

One can construct a Description from a String or a string slice, an iterator thereof, or from an iterator over other Descriptions:

let single_element_description: Description =
    "A single block description".into();
let two_element_description: Description =
    ["First item", "Second item"].into_iter().collect();
let two_element_description_from_strings: Description =
    ["First item".to_string(), "Second item".to_string()].into_iter().collect();

No newline is added after the last element during rendering. This makes it easier to support single-line matcher descriptions and match explanations.

Implementations§

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impl Description

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pub fn new() -> Self

Returns a new empty Description.

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pub fn text(self, text: impl Into<Cow<'static, str>>) -> Self

Appends a block of text to this instance.

The block is indented uniformly when this instance is rendered.

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pub fn nested(self, inner: Description) -> Self

Appends a nested Description to this instance.

The nested Description inner is indented uniformly at the next level of indentation when this instance is rendered.

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pub fn collect(self, inner: impl IntoIterator<Item = Description>) -> Self

Appends all Description in the given sequence inner to this instance.

Each element is treated as a nested Description in the sense of Self::nested.

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pub fn indent(self) -> Self

Indents the lines in elements of this description.

This operation will be performed lazily when self is displayed.

This will indent every line inside each element.

For example:

let description = std::iter::once("A B C\nD E F".to_string()).collect::<Description>();
verify_that!(description.indent(), displays_as(eq("  A B C\n  D E F")))

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pub fn bullet_list(self) -> Self

Instructs this instance to render its elements as a bullet list.

Each element (from either Description::text or Description::nested) is rendered as a bullet point. If an element contains multiple lines, the following lines are aligned with the first one in the block.

For instance:

let description = Description::new()
    .text("First line\nsecond line")
    .bullet_list();
verify_that!(description, displays_as(eq("\
* First line
  second line")))

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pub fn enumerate(self) -> Self

Instructs this instance to render its elements as an enumerated list.

Each element (from either Description::text or Description::nested) is rendered with its zero-based index. If an element contains multiple lines, the following lines are aligned with the first one in the block.

For instance:

let description = Description::new()
    .text("First line\nsecond line")
    .enumerate();
verify_that!(description, displays_as(eq("\
0. First line
   second line")))

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