nushell/crates/nu-std/std/assert.nu

##################################################################################
#
# Assert commands.
#
##################################################################################

# Universal assert command
#
# If the condition is not true, it generates an error.
#
# # Example
#
# ```nushell
# >_ assert (3 == 3)
# >_ assert (42 == 3)
# Error:
#   × Assertion failed:
#     ╭─[myscript.nu:11:1]
#  11 │ assert (3 == 3)
#  12 │ assert (42 == 3)
#     ·         ───┬────
#     ·            ╰── It is not true.
#  13 │
#     ╰────
# ```
#
# The --error-label flag can be used if you want to create a custom assert command:
# ```
# def "assert even" [number: int] {
#     assert ($number mod 2 == 0) --error-label {
#         start: (metadata $number).span.start,
#         end: (metadata $number).span.end,
#         text: $"($number) is not an even number",
#     }
# }
# ```
export def main [
    condition: bool, # Condition, which should be true
    message?: string, # Optional error message
    --error-label: record # Label for `error make` if you want to create a custom assert
] {
    if $condition { return }
    let span = (metadata $condition).span
    error make {
        msg: ($message | default "Assertion failed."),
        label: ($error_label | default {
            text: "It is not true.",
            start: $span.start,
            end: $span.end
        })
    }
}


# Negative assertion
#
# If the condition is not false, it generates an error.
#
# # Examples
#
# >_ assert (42 == 3)
# >_ assert (3 == 3)
# Error:
#   × Assertion failed:
#     ╭─[myscript.nu:11:1]
#  11 │ assert (42 == 3)
#  12 │ assert (3 == 3)
#     ·         ───┬────
#     ·            ╰── It is not false.
#  13 │
#     ╰────
#
#
# The --error-label flag can be used if you want to create a custom assert command:
# ```
# def "assert not even" [number: int] {
#     assert not ($number mod 2 == 0) --error-label {
#         start: (metadata $number).span.start,
#         end: (metadata $number).span.end,
#         text: $"($number) is an even number",
#     }
# }
# ```
#
export def not [
    condition: bool, # Condition, which should be false
    message?: string, # Optional error message
    --error-label: record # Label for `error make` if you want to create a custom assert
] {
    if $condition {
        let span = (metadata $condition).span
        error make {
            msg: ($message | default "Assertion failed."),
            label: ($error_label | default {
                text: "It is not false.",
                start: $span.start,
                end: $span.end
            })
        }
    }
}

# Assert that executing the code generates an error
#
# For more documentation see the assert command
#
# # Examples
#
# > assert error {|| missing_command} # passes
# > assert error {|| 12} # fails
export def error [
    code: closure,
    message?: string
] {
    let error_raised = (try { do $code; false } catch { true })
    main ($error_raised) $message --error-label {
        start: (metadata $code).span.start
        end: (metadata $code).span.end
        text: $"There were no error during code execution: (view source $code)"
    }
}

# Assert $left == $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert equal 1 1 # passes
# > assert equal (0.1 + 0.2) 0.3
# > assert equal 1 2 # fails
export def equal [left: any, right: any, message?: string] {
    main ($left == $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"They are not equal. Left = '($left)'. Right = '($right)'."
    }
}

# Assert $left != $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert not equal 1 2 # passes
# > assert not equal 1 "apple" # passes
# > assert not equal 7 7 # fails
export def "not equal" [left: any, right: any, message?: string] {
    main ($left != $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"They both are '($left)'."
    }
}

# Assert $left <= $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert less or equal 1 2 # passes
# > assert less or equal 1 1 # passes
# > assert less or equal 1 0 # fails
export def "less or equal" [left: any, right: any, message?: string] {
    main ($left <= $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"Left: '($left)', Right: '($right)'"
    }
}

# Assert $left < $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert less 1 2 # passes
# > assert less 1 1 # fails
export def less [left: any, right: any, message?: string] {
    main ($left < $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"Left: '($left)', Right: '($right)'"
    }
}

# Assert $left > $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert greater 2 1 # passes
# > assert greater 2 2 # fails
export def greater [left: any, right: any, message?: string] {
    main ($left > $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"Left: '($left)', Right: '($right)'"
    }
}

# Assert $left >= $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert greater or equal 2 1 # passes
# > assert greater or equal 2 2 # passes
# > assert greater or equal 1 2 # fails
export def "greater or equal" [left: any, right: any, message?: string] {
    main ($left >= $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"Left: '($left)', Right: '($right)'"
    }
}

alias "core length" = length
# Assert length of $left is $right
#
# For more documentation see the assert command
#
# # Examples
#
# > assert length [0, 0] 2 # passes
# > assert length [0] 3 # fails
export def length [left: list, right: int, message?: string] {
    main (($left | core length) == $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"Length of ($left) is ($left | core length), not ($right)"
    }
}

alias "core str contains" = str contains
# Assert that ($left | str contains $right)
#
# For more documentation see the assert command
#
# # Examples
#
# > assert str contains "arst" "rs" # passes
# > assert str contains "arst" "k" # fails
export def "str contains" [left: string, right: string, message?: string] {
    main ($left | core str contains $right) $message --error-label {
        start: (metadata $left).span.start
        end: (metadata $right).span.end
        text: $"'($left)' does not contain '($right)'."
    }
}