Add end_with matcher

This commit is contained in:
Michael Miller 2019-01-31 22:05:27 -07:00
parent e6e4f28a4c
commit d0711f940d
2 changed files with 94 additions and 0 deletions

View file

@ -305,5 +305,27 @@ module Spectator::DSL
macro start_with(expected) macro start_with(expected)
::Spectator::Matchers::StartWithMatcher.new({{expected.stringify}}, {{expected}}) ::Spectator::Matchers::StartWithMatcher.new({{expected.stringify}}, {{expected}})
end end
# Indicates that some value or set should end with another value.
# This is typically used on a `String` or `Array` (any `Indexable` works).
# The `expected` argument can be a `String`, `Char`, or `Regex`
# when the actual type (being comapred against) is a `String`.
# For `Indexable` types, only the last item is inspected.
# It is compared with the `===` operator,
# so that values, types, regular expressions, and others can be tested.
#
# Examples:
# ```
# expect("foobar").to end_with("bar")
# expect("foobar").to end_with('r')
# expect("FOOBAR").to end_with(/bar/i)
#
# expect(%i[a b c]).to end_with(:c)
# expect(%i[a b c]).to end_with(Symbol)
# expect(%w[foo bar]).to end_with(/bar/)
# ```
macro end_with(expected)
::Spectator::Matchers::EndWithMatcher.new({{expected.stringify}}, {{expected}})
end
end end
end end

View file

@ -0,0 +1,72 @@
require "./value_matcher"
module Spectator::Matchers
# Matcher that tests whether a value, such as a `String` or `Array`, ends with a value.
# The `ends_with?` method is used if it's defined on the actual type.
# Otherwise, it is treated as an `Indexable` and the `last` value is compared against.
struct EndWithMatcher(ExpectedType) < ValueMatcher(ExpectedType)
# Determines whether the matcher is satisfied with the value given to it.
# True is returned if the match was successful, false otherwise.
def match?(partial)
actual = partial.actual
compare_method(actual, &.eval(actual, expected))
end
# Describes the condition that satisfies the matcher.
# This is informational and displayed to the end-user.
def message(partial)
method_string = compare_method(partial.actual, &.to_s)
"Expected #{partial.label} to end with #{label} (using #{method_string})"
end
# Describes the condition that won't satsify the matcher.
# This is informational and displayed to the end-user.
def negated_message(partial)
method_string = compare_method(partial.actual, &.to_s)
"Expected #{partial.label} to not end with #{label} (using #{method_string})"
end
# Returns the method that should be used for comparison.
# Call `eval(actual, expected)` on the returned value.
private macro compare_method(actual, &block)
# If the actual type defines `ends_with?`,
# then use that for the comparison.
# Otherwise, treat the actual type as an `Indexable`,
# and retrieve the last value to compare with.
# FIXME: Is there a better way to do this?
if {{actual}}.responds_to?(:starts_with?)
{{block.args.first}} = EndsWithCompareMethod.new
{{block.body}}
else
{{block.args.first}} = IndexableCompareMethod.new
{{block.body}}
end
end
# Comparison method for types that define the `ends_with?` method.
private struct EndsWithCompareMethod
# Evaluates the condition to determine whether the matcher is satisfied.
def eval(actual, expected)
actual.ends_with?(expected)
end
# String representation for end-user output.
def to_s
"#starts_with?"
end
end
# Comparison method for `Indexable` types.
private struct IndexableCompareMethod
# Evaluates the condition to determine whether the matcher is satisfied.
def eval(actual, expected)
expected === actual.last
end
# String representation for end-user output.
def to_s
"expected === actual.last"
end
end
end
end