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Containment assertions

The contains family, shared by strings, collections, dicts, and bytes.

Containment assertions mixin.

contains 

contains(*items: object) -> Self

Asserts that val contains the given item or items.

Checks if the collection contains the given item or items using in operator.

Parameters:

Name Type Description Default
*items object

the item or items expected to be contained

 ()

Examples:

Usage:

assert_that('foo').contains('f')
assert_that('foo').contains('f', 'oo')
assert_that(['a', 'b']).contains('b', 'a')
assert_that((1, 2, 3)).contains(3, 2, 1)
assert_that({'a': 1, 'b': 2}).contains('b', 'a')  # checks keys
assert_that({'a', 'b'}).contains('b', 'a')
assert_that([1, 2, 3]).is_type_of(list).contains(1, 2).does_not_contain(4, 5)

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does not contain the item or items
Tip

Use the contains_key() alias when working with dict-like objects to be self-documenting.

See Also

contains_ignoring_case() - for case-insensitive string contains

Source code in assertpy2/contains.py 
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def contains(self, *items: object) -> Self:
    """Asserts that val contains the given item or items.

    Checks if the collection contains the given item or items using ``in`` operator.

    Args:
        *items: the item or items expected to be contained

    Examples:
        Usage:

            assert_that('foo').contains('f')
            assert_that('foo').contains('f', 'oo')
            assert_that(['a', 'b']).contains('b', 'a')
            assert_that((1, 2, 3)).contains(3, 2, 1)
            assert_that({'a': 1, 'b': 2}).contains('b', 'a')  # checks keys
            assert_that({'a', 'b'}).contains('b', 'a')
            assert_that([1, 2, 3]).is_type_of(list).contains(1, 2).does_not_contain(4, 5)

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val does **not** contain the item or items

    Tip:
        Use the [`contains_key()`][assertpy2.dict.DictMixin.contains_key] alias when working with
        *dict-like* objects to be self-documenting.

    See Also:
        [`contains_ignoring_case()`][assertpy2.string.StringMixin.contains_ignoring_case] -
            for case-insensitive string contains
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    elif len(items) == 1:
        item = items[0]
        if isinstance(item, Matcher):
            if not any(item.matches(value) for value in self.val):
                diff = DiffResult(
                    kind="contains", entries=[DiffEntry(path="missing", actual=None, expected=item.describe())]
                )
                return self.error(
                    f"Expected <{self.val}> to contain item matching {item.describe()}, but did not.",
                    diff=diff,
                )
        elif item not in self.val:
            diff = DiffResult(kind="contains", entries=[DiffEntry(path="missing", actual=None, expected=item)])
            if self._is_dict_like(self.val):
                return self.error(f"Expected <{self.val}> to contain key <{item}>, but did not.", diff=diff)
            else:
                return self.error(f"Expected <{self.val}> to contain item <{item}>, but did not.", diff=diff)
    else:
        missing = []
        for item in items:
            if isinstance(item, Matcher):
                if not any(item.matches(value) for value in self.val):
                    missing.append(item)
            elif item not in self.val:
                missing.append(item)
        if missing:
            missing_desc = [
                missing_item.describe() if isinstance(missing_item, Matcher) else missing_item
                for missing_item in missing
            ]
            diff = DiffResult(
                kind="contains",
                entries=[
                    DiffEntry(path="missing", actual=None, expected=missing_item) for missing_item in missing_desc
                ],
            )
            if self._is_dict_like(self.val):
                return self.error(
                    f"Expected <{self.val}> to contain keys {self._fmt_items(items)}, but did not contain"
                    f" key{'' if len(missing) == 1 else 's'} {self._fmt_items(missing_desc)}.",
                    diff=diff,
                )
            else:
                return self.error(
                    f"Expected <{self.val}> to contain items {self._fmt_items(items)},"
                    f" but did not contain {self._fmt_items(missing_desc)}.",
                    diff=diff,
                )
    return self

does_not_contain 

does_not_contain(*items: object) -> Self

Asserts that val does not contain the given item or items.

Checks if the collection excludes the given item or items using in operator.

Parameters:

Name Type Description Default
*items object

the item or items expected to be excluded

 ()

Examples:

Usage:

assert_that('foo').does_not_contain('x')
assert_that(['a', 'b']).does_not_contain('x', 'y')
assert_that((1, 2, 3)).does_not_contain(4, 5)
assert_that({'a': 1, 'b': 2}).does_not_contain('x', 'y')  # checks keys
assert_that({'a', 'b'}).does_not_contain('x', 'y')
assert_that([1, 2, 3]).is_type_of(list).contains(1, 2).does_not_contain(4, 5)

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does contain the item or items
Tip

Use the does_not_contain_key() alias when working with dict-like objects to be self-documenting.

Source code in assertpy2/contains.py 
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def does_not_contain(self, *items: object) -> Self:
    """Asserts that val does not contain the given item or items.

    Checks if the collection excludes the given item or items using ``in`` operator.

    Args:
        *items: the item or items expected to be excluded

    Examples:
        Usage:

            assert_that('foo').does_not_contain('x')
            assert_that(['a', 'b']).does_not_contain('x', 'y')
            assert_that((1, 2, 3)).does_not_contain(4, 5)
            assert_that({'a': 1, 'b': 2}).does_not_contain('x', 'y')  # checks keys
            assert_that({'a', 'b'}).does_not_contain('x', 'y')
            assert_that([1, 2, 3]).is_type_of(list).contains(1, 2).does_not_contain(4, 5)

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val **does** contain the item or items

    Tip:
        Use the [`does_not_contain_key()`][assertpy2.dict.DictMixin.does_not_contain_key] alias when working with
        *dict-like* objects to be self-documenting.
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    elif len(items) == 1:
        if items[0] in self.val:
            return self.error(f"Expected <{self.val}> to not contain item <{items[0]}>, but did.")
    else:
        found = [item for item in items if item in self.val]
        if found:
            return self.error(
                f"Expected <{self.val}> to not contain items {self._fmt_items(items)},"
                f" but did contain {self._fmt_items(found)}."
            )
    return self

contains_only 

contains_only(*items: object) -> Self

Asserts that val contains only the given item or items.

Checks if the collection contains only the given item or items using in operator.

Parameters:

Name Type Description Default
*items object

the only item or items expected to be contained

 ()

Examples:

Usage:

assert_that('foo').contains_only('f', 'o')
assert_that(['a', 'a', 'b']).contains_only('a', 'b')
assert_that((1, 1, 2)).contains_only(1, 2)
assert_that({'a': 1, 'a': 2, 'b': 3}).contains_only('a', 'b')
assert_that({'a', 'a', 'b'}).contains_only('a', 'b')

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val contains anything not item or items
Source code in assertpy2/contains.py 
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def contains_only(self, *items: object) -> Self:
    """Asserts that val contains *only* the given item or items.

    Checks if the collection contains only the given item or items using ``in`` operator.

    Args:
        *items: the *only* item or items expected to be contained

    Examples:
        Usage:

            assert_that('foo').contains_only('f', 'o')
            assert_that(['a', 'a', 'b']).contains_only('a', 'b')
            assert_that((1, 1, 2)).contains_only(1, 2)
            assert_that({'a': 1, 'a': 2, 'b': 3}).contains_only('a', 'b')
            assert_that({'a', 'a', 'b'}).contains_only('a', 'b')

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val contains anything **not** item or items
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    else:
        extra = [item for item in self.val if item not in items]
        if extra:
            return self.error(
                f"Expected <{self.val}> to contain only {self._fmt_items(items)},"
                f" but did contain {self._fmt_items(extra)}."
            )

        missing = [item for item in items if item not in self.val]
        if missing:
            return self.error(
                f"Expected <{self.val}> to contain only {self._fmt_items(items)},"
                f" but did not contain {self._fmt_items(missing)}."
            )
    return self

contains_sequence 

contains_sequence(*items: object) -> Self

Asserts that val contains the given ordered sequence of items.

Checks if the collection contains the given sequence of items using in operator.

Parameters:

Name Type Description Default
*items object

the sequence of items expected to be contained

 ()

Examples:

Usage:

assert_that('foo').contains_sequence('f', 'o')
assert_that('foo').contains_sequence('o', 'o')
assert_that(['a', 'b', 'c']).contains_sequence('b', 'c')
assert_that((1, 2, 3)).contains_sequence(1, 2)

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does not contains the given sequence of items
Source code in assertpy2/contains.py 
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def contains_sequence(self, *items: object) -> Self:
    """Asserts that val contains the given ordered sequence of items.

    Checks if the collection contains the given sequence of items using ``in`` operator.

    Args:
        *items: the sequence of items expected to be contained

    Examples:
        Usage:

            assert_that('foo').contains_sequence('f', 'o')
            assert_that('foo').contains_sequence('o', 'o')
            assert_that(['a', 'b', 'c']).contains_sequence('b', 'c')
            assert_that((1, 2, 3)).contains_sequence(1, 2)

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val does **not** contains the given sequence of items
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    if isinstance(self.val, str):
        search_start = 0
        for item in items:
            if not isinstance(item, str):
                raise TypeError("given args must be strings when val is a string")
            found_index = self.val.find(item, search_start)
            if found_index == -1:
                return self.error(
                    f"Expected <{self.val}> to contain sequence {self._fmt_items(items)}, but did not."
                )
            search_start = found_index + len(item)
        return self
    try:
        for i in range(len(self.val) - len(items) + 1):
            for j in range(len(items)):
                if self.val[i + j] != items[j]:
                    break
            else:
                return self
    except TypeError:
        raise TypeError("val is not iterable") from None
    return self.error(f"Expected <{self.val}> to contain sequence {self._fmt_items(items)}, but did not.")

contains_duplicates 

contains_duplicates() -> Self

Asserts that val is iterable and does contain duplicates.

Examples:

Usage:

assert_that('foo').contains_duplicates()
assert_that(['a', 'a', 'b']).contains_duplicates()
assert_that((1, 1, 2)).contains_duplicates()

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does not contain any duplicates
Source code in assertpy2/contains.py 
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def contains_duplicates(self) -> Self:
    """Asserts that val is iterable and *does* contain duplicates.

    Examples:
        Usage:

            assert_that('foo').contains_duplicates()
            assert_that(['a', 'a', 'b']).contains_duplicates()
            assert_that((1, 1, 2)).contains_duplicates()

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val does **not** contain any duplicates
    """
    try:
        if len(self.val) != len(set(self.val)):
            return self
    except TypeError:
        raise TypeError("val is not iterable") from None
    return self.error(f"Expected <{self.val}> to contain duplicates, but did not.")

does_not_contain_duplicates 

does_not_contain_duplicates() -> Self

Asserts that val is iterable and does not contain any duplicates.

Examples:

Usage:

assert_that('fox').does_not_contain_duplicates()
assert_that(['a', 'b', 'c']).does_not_contain_duplicates()
assert_that((1, 2, 3)).does_not_contain_duplicates()

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does contain duplicates
Source code in assertpy2/contains.py 
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def does_not_contain_duplicates(self) -> Self:
    """Asserts that val is iterable and *does not* contain any duplicates.

    Examples:
        Usage:

            assert_that('fox').does_not_contain_duplicates()
            assert_that(['a', 'b', 'c']).does_not_contain_duplicates()
            assert_that((1, 2, 3)).does_not_contain_duplicates()

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val **does** contain duplicates
    """
    try:
        if len(self.val) == len(set(self.val)):
            return self
    except TypeError:
        raise TypeError("val is not iterable") from None
    return self.error(f"Expected <{self.val}> to not contain duplicates, but did.")

is_empty 

is_empty() -> Self

Asserts that val is empty.

Examples:

Usage:

assert_that('').is_empty()
assert_that([]).is_empty()
assert_that(()).is_empty()
assert_that({}).is_empty()
assert_that(set()).is_empty()

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val is not empty
Source code in assertpy2/contains.py 
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def is_empty(self) -> Self:
    """Asserts that val is empty.

    Examples:
        Usage:

            assert_that('').is_empty()
            assert_that([]).is_empty()
            assert_that(()).is_empty()
            assert_that({}).is_empty()
            assert_that(set()).is_empty()

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val is **not** empty
    """
    if len(self.val) != 0:
        if isinstance(self.val, str):
            return self.error(f"Expected <{self.val}> to be empty string, but was not.")
        else:
            return self.error(f"Expected <{self.val}> to be empty, but was not.")
    return self

is_not_empty 

is_not_empty() -> Self

Asserts that val is not empty.

Examples:

Usage:

assert_that('foo').is_not_empty()
assert_that(['a', 'b']).is_not_empty()
assert_that((1, 2, 3)).is_not_empty()
assert_that({'a': 1, 'b': 2}).is_not_empty()
assert_that({'a', 'b'}).is_not_empty()

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val is empty
Source code in assertpy2/contains.py 
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def is_not_empty(self) -> Self:
    """Asserts that val is *not* empty.

    Examples:
        Usage:

            assert_that('foo').is_not_empty()
            assert_that(['a', 'b']).is_not_empty()
            assert_that((1, 2, 3)).is_not_empty()
            assert_that({'a': 1, 'b': 2}).is_not_empty()
            assert_that({'a', 'b'}).is_not_empty()

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val **is** empty
    """
    if len(self.val) == 0:
        if isinstance(self.val, str):
            return self.error("Expected not empty string, but was empty.")
        else:
            return self.error("Expected not empty, but was empty.")
    return self

contains_exactly 

contains_exactly(*items: object) -> Self

Asserts that val contains exactly the given items in the given order.

Unlike contains_only() (which ignores order) and contains_sequence() (which allows extra items), this method requires exact count, items, and order.

Parameters:

Name Type Description Default
*items object

the items expected, in exact order

 ()

Examples:

Usage:

assert_that([1, 2, 3]).contains_exactly(1, 2, 3)
assert_that(['a', 'b']).contains_exactly('a', 'b')

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does not contain exactly the given items in order
Source code in assertpy2/contains.py 
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def contains_exactly(self, *items: object) -> Self:
    """Asserts that val contains exactly the given items in the given order.

    Unlike [`contains_only()`][assertpy2.contains.ContainsMixin.contains_only] (which ignores
    order) and [`contains_sequence()`][assertpy2.contains.ContainsMixin.contains_sequence]
    (which allows extra items), this method requires exact count, items, and order.

    Args:
        *items: the items expected, in exact order

    Examples:
        Usage:

            assert_that([1, 2, 3]).contains_exactly(1, 2, 3)
            assert_that(['a', 'b']).contains_exactly('a', 'b')

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val does **not** contain exactly the given items in order
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    try:
        val_list = list(self.val)
    except TypeError:
        raise TypeError("val is not iterable") from None
    if val_list != list(items):
        val_counts = Counter(val_list)
        item_counts = Counter(items)
        entries = [
            DiffEntry(path="extra", actual=item, expected=None)
            for item in sorted((val_counts - item_counts).elements(), key=repr)
        ]
        entries.extend(
            DiffEntry(path="missing", actual=None, expected=item)
            for item in sorted((item_counts - val_counts).elements(), key=repr)
        )
        diff = DiffResult(kind="contains", entries=entries) if entries else None
        return self.error(
            f"Expected <{self.val}> to contain exactly {self._fmt_items(items)}, but did not.",
            diff=diff,
        )
    return self

contains_in_order 

contains_in_order(*items: object) -> Self

Asserts that val contains the given items in the given order (as a subsequence).

Items must appear in the given order but do not need to be contiguous. Unlike contains_sequence() which requires contiguous items.

Parameters:

Name Type Description Default
*items object

the items expected, in order (but not necessarily contiguous)

 ()

Examples:

Usage:

assert_that([1, 5, 2, 8, 3]).contains_in_order(1, 2, 3)
assert_that(['a', 'x', 'b', 'y', 'c']).contains_in_order('a', 'b', 'c')

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val does not contain items in the given order
Source code in assertpy2/contains.py 
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def contains_in_order(self, *items: object) -> Self:
    """Asserts that val contains the given items in the given order (as a subsequence).

    Items must appear in the given order but do not need to be contiguous.
    Unlike [`contains_sequence()`][assertpy2.contains.ContainsMixin.contains_sequence] which
    requires contiguous items.

    Args:
        *items: the items expected, in order (but not necessarily contiguous)

    Examples:
        Usage:

            assert_that([1, 5, 2, 8, 3]).contains_in_order(1, 2, 3)
            assert_that(['a', 'x', 'b', 'y', 'c']).contains_in_order('a', 'b', 'c')

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val does **not** contain items in the given order
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    try:
        val_list = list(self.val)
    except TypeError:
        raise TypeError("val is not iterable") from None
    item_index = 0
    for element in val_list:
        if item_index < len(items) and element == items[item_index]:
            item_index += 1
    if item_index != len(items):
        return self.error(f"Expected <{self.val}> to contain {self._fmt_items(items)} in order, but did not.")
    return self

contains_only_once 

contains_only_once(*items: object) -> Self

Asserts that val contains each given item exactly once.

Each given item must appear in val with a count of exactly one: an item absent from val is reported as missing, an item occurring more than once is reported as duplicated.

Parameters:

Name Type Description Default
*items object

the items each expected to occur exactly once

 ()

Examples:

Usage:

assert_that([1, 2, 3]).contains_only_once(1, 3)
assert_that('foo').contains_only_once('f')

assert_that([1, 2, 2, 3]).contains_only_once(2)  # fails (occurs twice)
assert_that([1, 2, 3]).contains_only_once(4)  # fails (missing)

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if any given item is missing from val or occurs more than once
TypeError

if val is not iterable
ValueError

if no items are given
Source code in assertpy2/contains.py 
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def contains_only_once(self, *items: object) -> Self:
    """Asserts that val contains each given item exactly once.

    Each given item must appear in val with a count of exactly one: an item absent from val is
    reported as missing, an item occurring more than once is reported as duplicated.

    Args:
        *items: the items each expected to occur exactly once

    Examples:
        Usage:

            assert_that([1, 2, 3]).contains_only_once(1, 3)
            assert_that('foo').contains_only_once('f')

            assert_that([1, 2, 2, 3]).contains_only_once(2)  # fails (occurs twice)
            assert_that([1, 2, 3]).contains_only_once(4)  # fails (missing)

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if any given item is missing from val or occurs more than once
        TypeError: if val is not iterable
        ValueError: if no items are given
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    try:
        val_list = list(self.val)
    except TypeError:
        raise TypeError("val is not iterable") from None
    counts = Counter(val_list)
    missing = [item for item in items if counts[item] == 0]
    duplicated = [item for item in items if counts[item] > 1]
    if missing or duplicated:
        entries = [DiffEntry(path="missing", actual=None, expected=item) for item in missing]
        entries.extend(DiffEntry(path="duplicated", actual=counts[item], expected=item) for item in duplicated)
        problems = []
        if missing:
            problems.append(f"did not contain {self._fmt_items(missing)}")
        if duplicated:
            problems.append(f"contained {self._fmt_items(duplicated)} more than once")
        return self.error(
            f"Expected <{self.val}> to contain {self._fmt_items(items)} only once, but {' and '.join(problems)}.",
            diff=DiffResult(kind="contains", entries=entries),
        )
    return self

is_in 

is_in(*items: object) -> Self

Asserts that val is equal to one of the given items.

Parameters:

Name Type Description Default
*items object

the items expected to contain val

 ()

Examples:

Usage:

assert_that('foo').is_in('foo', 'bar', 'baz')
assert_that(1).is_in(0, 1, 2, 3)

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val is not in the given items
Source code in assertpy2/contains.py 
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def is_in(self, *items: object) -> Self:
    """Asserts that val is equal to one of the given items.

    Args:
        *items: the items expected to contain val

    Examples:
        Usage:

            assert_that('foo').is_in('foo', 'bar', 'baz')
            assert_that(1).is_in(0, 1, 2, 3)

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val is **not** in the given items
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    else:
        for item in items:
            if self.val == item:
                return self
    return self.error(f"Expected <{self.val}> to be in {self._fmt_items(items)}, but was not.")

is_not_in 

is_not_in(*items: object) -> Self

Asserts that val is not equal to one of the given items.

Parameters:

Name Type Description Default
*items object

the items expected to exclude val

 ()

Examples:

Usage:

assert_that('foo').is_not_in('bar', 'baz', 'box')
assert_that(1).is_not_in(-1, -2, -3)

Returns:

Name Type Description
AssertionBuilder Self

returns this instance to chain to the next assertion

Raises:

Type Description
AssertionError

if val is in the given items
Source code in assertpy2/contains.py 
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def is_not_in(self, *items: object) -> Self:
    """Asserts that val is not equal to one of the given items.

    Args:
        *items: the items expected to exclude val

    Examples:
        Usage:

            assert_that('foo').is_not_in('bar', 'baz', 'box')
            assert_that(1).is_not_in(-1, -2, -3)

    Returns:
        AssertionBuilder: returns this instance to chain to the next assertion

    Raises:
        AssertionError: if val **is** in the given items
    """
    if len(items) == 0:
        raise ValueError("one or more args must be given")
    else:
        for item in items:
            if self.val == item:
                return self.error(f"Expected <{self.val}> to not be in {self._fmt_items(items)}, but was.")
    return self