48 lines
1.7 KiB
Crystal
48 lines
1.7 KiB
Crystal
require "./matcher"
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module Spectator::Matchers
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# Matcher that tests whether a collection is empty.
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# The values are checked with the `empty?` method.
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struct EmptyMatcher < StandardMatcher
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# Short text about the matcher's purpose.
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# This explains what condition satisfies the matcher.
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# The description is used when the one-liner syntax is used.
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def description : String
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"is empty"
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end
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# Checks whether the matcher is satisfied with the expression given to it.
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private def match?(actual : Expression(T)) : Bool forall T
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actual_value = actual.value
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return unexpected(actual_value, actual.label) unless actual_value.responds_to?(:empty?)
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actual_value.empty?
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end
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# Message displayed when the matcher isn't satisfied.
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#
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# This is only called when `#match?` returns false.
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#
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# The message should typically only contain the test expression labels.
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# Actual values should be returned by `#values`.
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private def failure_message(actual) : String
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"#{actual.label} is not empty"
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end
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# Message displayed when the matcher isn't satisfied and is negated.
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# This is essentially what would satisfy the matcher if it wasn't negated.
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#
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# This is only called when `#does_not_match?` returns false.
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#
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# The message should typically only contain the test expression labels.
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# Actual values should be returned by `#values`.
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private def failure_message_when_negated(actual) : String
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"#{actual.label} is empty"
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end
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private def unexpected(value, label)
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raise "#{label} is not a collection (must respond to `#empty?`). #{label}: #{value.inspect}"
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end
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end
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end
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