Core API¶

Helpers
- hasmethod
- wrap_matcher

BaseDescription¶

class hamcrest.core.base_description.BaseDescription¶

Bases: hamcrest.core.description.Description

Base class for all Description implementations.

append(string: str) → None¶: Append the string to the description.

append_description_of(value: Any) → hamcrest.core.description.Description¶

Appends description of given value to this description.

If the value implements describe_to, then it will be used.

Returns:	`self`, for chaining

append_list(start: str, separator: str, end: str, list: Iterable[Any]) → hamcrest.core.description.Description¶

Appends a list of objects to the description.

Parameters:	start – String that will begin the list description. separator – String that will separate each object in the description. end – String that will end the list description. list – List of objects to be described.
Returns:	`self`, for chaining

append_text(text: str) → hamcrest.core.description.Description¶

Appends some plain text to the description.

Returns:	`self`, for chaining

BaseMatcher¶

class hamcrest.core.base_matcher.BaseMatcher¶

Bases: hamcrest.core.matcher.Matcher

Base class for all Matcher implementations.

Most implementations can just implement _matches, leaving the handling of any mismatch description to the matches method. But if it makes more sense to generate the mismatch description during the matching, override matches instead.

_matches(item: T) → bool¶

describe_match(item: T, match_description: hamcrest.core.description.Description) → None¶

Generates a description of why the matcher has accepted the item.

The description may be part of a larger description of why a matching failed, so it should be concise.

This method assumes that matches(item) is True, but will not check this.

Parameters:	item – The item that the `Matcher` has accepted. match_description – The description to be built or appended to.

describe_mismatch(item: T, mismatch_description: hamcrest.core.description.Description) → None¶

Generates a description of why the matcher has not accepted the item.

The description will be part of a larger description of why a matching failed, so it should be concise.

This method assumes that matches(item) is False, but will not check this.

Parameters:	item – The item that the `Matcher` has rejected. mismatch_description – The description to be built or appended to.

matches(item: T, mismatch_description: Optional[hamcrest.core.description.Description] = None) → bool¶

Evaluates the matcher for argument item.

If a mismatch is detected and argument mismatch_description is provided, it will generate a description of why the matcher has not accepted the item.

Parameters:	item – The object against which the matcher is evaluated. mismatch_description –
Returns:	`True` if `item` matches, otherwise `False`.

Description¶

class hamcrest.core.description.Description¶

Bases: object

A description of a Matcher.

A Matcher will describe itself to a description which can later be used for reporting.

append_description_of(value: Any) → hamcrest.core.description.Description¶

Appends description of given value to this description.

If the value implements describe_to, then it will be used.

Returns:	`self`, for chaining

append_list(start: str, separator: str, end: str, list: Iterable[Any]) → hamcrest.core.description.Description¶

Appends a list of objects to the description.

Parameters:	start – String that will begin the list description. separator – String that will separate each object in the description. end – String that will end the list description. list – List of objects to be described.
Returns:	`self`, for chaining

append_text(text: str) → hamcrest.core.description.Description¶

Appends some plain text to the description.

Returns:	`self`, for chaining

Matcher¶

class hamcrest.core.matcher.Matcher¶

Bases: typing.Generic, hamcrest.core.selfdescribing.SelfDescribing

A matcher over acceptable values.

A matcher is able to describe itself to give feedback when it fails.

Matcher implementations should not directly implement this protocol. Instead, extend the BaseMatcher class, which will ensure that the Matcher API can grow to support new features and remain compatible with all Matcher implementations.

describe_match(item: T, match_description: hamcrest.core.description.Description) → None¶

Generates a description of why the matcher has accepted the item.

The description may be part of a larger description of why a matching failed, so it should be concise.

This method assumes that matches(item) is True, but will not check this.

Parameters:	item – The item that the `Matcher` has accepted. match_description – The description to be built or appended to.

describe_mismatch(item: T, mismatch_description: hamcrest.core.description.Description) → None¶

Generates a description of why the matcher has not accepted the item.

The description will be part of a larger description of why a matching failed, so it should be concise.

This method assumes that matches(item) is False, but will not check this.

Parameters:	item – The item that the `Matcher` has rejected. mismatch_description – The description to be built or appended to.

matches(item: T, mismatch_description: Optional[hamcrest.core.description.Description] = None) → bool¶

Evaluates the matcher for argument item.

If a mismatch is detected and argument mismatch_description is provided, it will generate a description of why the matcher has not accepted the item.

Parameters:	item – The object against which the matcher is evaluated. mismatch_description –
Returns:	`True` if `item` matches, otherwise `False`.

SelfDescribing¶

class hamcrest.core.selfdescribing.SelfDescribing¶

Bases: object

The ability of an object to describe itself.

describe_to(description: hamcrest.core.description.Description) → None¶

Generates a description of the object.

The description may be part of a description of a larger object of which this is just a component, so it should be worded appropriately.

Parameters:	description – The description to be built or appended to.

SelfDescribingValue¶

class hamcrest.core.selfdescribingvalue.SelfDescribingValue(value: Any)¶

Bases: hamcrest.core.selfdescribing.SelfDescribing

Wrap any value in a SelfDescribingValue to satisfy the SelfDescribing interface.

Deprecated: No need for this class now that append_description_of handles any type of value.

describe_to(description: hamcrest.core.description.Description) → None¶: Generates a description of the value.

StringDescription¶

class hamcrest.core.string_description.StringDescription¶

Bases: hamcrest.core.base_description.BaseDescription

A Description that is stored as a string.

append(string: str) → None¶: Append the string to the description.

hamcrest.core.string_description.tostring(selfdescribing: hamcrest.core.selfdescribing.SelfDescribing) → str¶

Returns the description of a SelfDescribing object as a string.

Parameters:	selfdescribing – The object to be described.
Returns:	The description of the object.