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Merge branch 'change-matchers' into 'release/0.8'

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Change matchers

See merge request arctic-fox/spectator!10
This commit is contained in:
Mike Miller 2019-08-12 05:12:51 +00:00
commit 454455d601
8 changed files with 514 additions and 36 deletions
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2
README.md
View file

@ -306,7 +306,7 @@ Items not marked as completed may have partial implementations.
- [ ] Misc. matchers
- [X] `match`
- [ ] `satisfy`
- [ ] `change[.by|.from[.to]|.to|.by_at_least|.by_at_most]`
- [X] `change[.by|.from[.to]|.to|.by_at_least|.by_at_most]`
- [X] `have_attributes`
- [ ] Compound - `and`, `or`
- [ ] Runner

20
src/spectator/dsl/example_dsl.cr
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@ -55,9 +55,6 @@ module Spectator::DSL
{% raise "Argument or block must be provided to expect" %}
{% end %}
# Create a proc to capture the block.
%proc = ->({{block.args.splat}}) {{block}}
# Check if the short-hand method syntax is used.
# This is a hack, since macros don't get this as a "literal" or something similar.
# The Crystal compiler will translate:
@ -73,16 +70,19 @@ module Spectator::DSL
# Extract the method name to make it clear to the user what is tested.
# The raw block can't be used because it's not clear to the user.
{% method_name = block.body.id.split('.')[1..-1].join('.') %}
%partial = %proc.partial(subject)
test_block = ::Spectator::TestBlock.create(%partial, {{"#" + method_name}})
{% else %}
%proc = ->{ subject.{{method_name.id}} }
%test_block = ::Spectator::TestBlock.create(%proc, {{"#" + method_name}})
{% elsif block.args.empty? %}
# In this case, it looks like the short-hand method syntax wasn't used.
# Just drop in the proc as-is.
test_block = ::Spectator::TestBlock.create(%proc, {{"`" + block.body.stringify + "`"}})
# Capture the block as a proc and pass along.
%proc = ->{{block}}
%test_block = ::Spectator::TestBlock.create(%proc, {{"`" + block.body.stringify + "`"}})
{% else %}
{% raise "Unexpected block arguments in expect call" %}
{% end %}
source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
::Spectator::Expectations::ExpectationPartial.new(test_block, source)
%source = ::Spectator::Source.new({{_source_file}}, {{_source_line}})
::Spectator::Expectations::ExpectationPartial.new(%test_block, %source)
end
# Starts an expectation.

140
src/spectator/dsl/matcher_dsl.cr
View file

@ -14,7 +14,8 @@ module Spectator::DSL
# expect(1 + 2).to eq(3)
# ```
macro eq(expected)
::Spectator::Matchers::EqualityMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::EqualityMatcher.new(%test_value)
end
# Indicates that some value should not equal another.
@ -26,7 +27,8 @@ module Spectator::DSL
# expect(1 + 2).to ne(5)
# ```
macro ne(expected)
::Spectator::Matchers::InequalityMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::InequalityMatcher.new(%test_value)
end
# Indicates that some value when compared to another satisfies an operator.
@ -60,7 +62,8 @@ module Spectator::DSL
# expect(obj.dup).to_not be(obj)
# ```
macro be(expected)
::Spectator::Matchers::ReferenceMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::ReferenceMatcher.new(%test_value)
end
# Indicates that some value should be of a specified type.
@ -117,7 +120,8 @@ module Spectator::DSL
# expect(3 - 1).to be_lt(3)
# ```
macro be_lt(expected)
::Spectator::Matchers::LessThanMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::LessThanMatcher.new(%test_value)
end
# Indicates that some value should be less than or equal to another.
@ -129,7 +133,8 @@ module Spectator::DSL
# expect(3 - 1).to be_le(3)
# ```
macro be_le(expected)
::Spectator::Matchers::LessThanEqualMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::LessThanEqualMatcher.new(%test_value)
end
# Indicates that some value should be greater than another.
@ -141,7 +146,8 @@ module Spectator::DSL
# expect(3 + 1).to be_gt(3)
# ```
macro be_gt(expected)
::Spectator::Matchers::GreaterThanMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::GreaterThanMatcher.new(%test_value)
end
# Indicates that some value should be greater than or equal to another.
@ -153,7 +159,8 @@ module Spectator::DSL
# expect(3 + 1).to be_ge(3)
# ```
macro be_ge(expected)
::Spectator::Matchers::GreaterThanEqualMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::GreaterThanEqualMatcher.new(%test_value)
end
# Indicates that some value should match another.
@ -170,7 +177,8 @@ module Spectator::DSL
# expect({:foo, 5}).to match({Symbol, Int32})
# ```
macro match(expected)
::Spectator::Matchers::CaseMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::CaseMatcher.new(%test_value)
end
# Indicates that some value should be true.
@ -260,7 +268,8 @@ module Spectator::DSL
# NOTE: Do not attempt to mix the two use cases.
# It likely won't work and will result in a compilation error.
macro be_within(expected)
::Spectator::Matchers::CollectionMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::CollectionMatcher.new(%test_value)
end
# Indicates that some value should be between a lower and upper-bound.
@ -280,10 +289,10 @@ module Spectator::DSL
# expect(100).to be_between(97, 101).exclusive # 97, 98, 99, or 100 (not 101)
# ```
macro be_between(min, max)
:Spectator::Matchers::RangeMatcher.new(
::Spectator::TestValue.new(Range.new({{min}}, {{max}})),
[{{min.stringify}}, {{max.stringify}}].join(" to ")
)
%range = Range.new({{min}}, {{max}}))
%label = [{{min.stringify}}, {{max.stringify}}].join(" to ")
%test_value = ::Spectator::TestValue.new(%range, %label)
:Spectator::Matchers::RangeMatcher.new(%test_value)
end
# Indicates that some value should be within a delta of an expected value.
@ -341,7 +350,8 @@ module Spectator::DSL
# expect(%w[foo bar]).to start_with(/foo/)
# ```
macro start_with(expected)
::Spectator::Matchers::StartWithMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::StartWithMatcher.new(%test_value)
end
# Indicates that some value or set should end with another value.
@ -363,7 +373,8 @@ module Spectator::DSL
# expect(%w[foo bar]).to end_with(/bar/)
# ```
macro end_with(expected)
::Spectator::Matchers::EndWithMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::EndWithMatcher.new(%test_value)
end
# Indicates that some value or set should contain another value.
@ -386,7 +397,8 @@ module Spectator::DSL
# expect(%i[a b c]).to contain(:a, :b)
# ```
macro contain(*expected)
::Spectator::Matchers::ContainMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.splat.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.splat.stringify}})
::Spectator::Matchers::ContainMatcher.new(%test_value)
end
# Indicates that some value or set should contain another value.
@ -415,7 +427,8 @@ module Spectator::DSL
# expect(%w[FOO BAR BAZ]).to have(/foo/i, String)
# ```
macro have(*expected)
::Spectator::Matchers::HaveMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.splat.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.splat.stringify}})
::Spectator::Matchers::HaveMatcher.new(%test_value)
end
# Indicates that some set, such as a `Hash`, has a given key.
@ -427,7 +440,8 @@ module Spectator::DSL
# expect({"lucky" => 7}).to have_key("lucky")
# ```
macro have_key(expected)
::Spectator::Matchers::HaveKeyMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::HaveKeyMatcher.new(%test_value)
end
# ditto
@ -444,7 +458,8 @@ module Spectator::DSL
# expect({"lucky" => 7}).to have_value(7)
# ```
macro have_value(expected)
::Spectator::Matchers::HaveValueMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::HaveValueMatcher.new(%test_value)
end
# ditto
@ -459,7 +474,8 @@ module Spectator::DSL
# expect([1, 2, 3]).to contain_exactly(1, 2, 3)
# ```
macro contain_exactly(*expected)
::Spectator::Matchers::ArrayMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::ArrayMatcher.new(%test_value)
end
# Indicates that some set should contain the same values in exact order as another set.
@ -469,7 +485,8 @@ module Spectator::DSL
# expect([1, 2, 3]).to match_array([1, 2, 3])
# ```
macro match_array(expected)
::Spectator::Matchers::ArrayMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::ArrayMatcher.new(%test_value)
end
# Indicates that some set should have a specified size.
@ -479,7 +496,8 @@ module Spectator::DSL
# expect([1, 2, 3]).to have_size(3)
# ```
macro have_size(expected)
::Spectator::Matchers::SizeMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.stringify}})
::Spectator::Matchers::SizeMatcher.new(%test_value)
end
# Indicates that some set should have the same size (number of elements) as another set.
@ -489,7 +507,8 @@ module Spectator::DSL
# expect([1, 2, 3]).to have_size_of(%i[x y z])
# ```
macro have_size_of(expected)
::Spectator::Matchers::SizeOfMatcher.new(::Spectator::TestValue.new(({{expected}}), {{expected.stringify}}))
%test_value = ::Spectator::TestValue.new(({{expected}}), {{expected.stringify}})
::Spectator::Matchers::SizeOfMatcher.new(%test_value)
end
# Indicates that some value should have a set of attributes matching some conditions.
@ -503,7 +522,77 @@ module Spectator::DSL
# expect(%i[a b c]).to have_attributes(size: 1..5, first: Symbol)
# ```
macro have_attributes(**expected)
::Spectator::Matchers::AttributesMatcher.new(::Spectator::TestValue.new({{expected}}, {{expected.double_splat.stringify}}))
%test_value = ::Spectator::TestValue.new({{expected}}, {{expected.double_splat.stringify}})
::Spectator::Matchers::AttributesMatcher.new(%test_value)
end
# Indicates that some expression's value should change after taking an action.
#
# Examples:
# ```
# i = 0
# expect { i += 1 }.to change { i }
# expect { i += 0 }.to_not change { i }
# ```
#
# ```
# i = 0
# expect { i += 5 }.to change { i }.from(0).to(5)
# ```
#
# ```
# i = 0
# expect { i += 5 }.to change { i }.to(5)
# ```
#
# ```
# i = 0
# expect { i += 5 }.to change { i }.from(0)
# ```
#
# ```
# i = 0
# expect { i += 42 }.to change { i }.by(42)
# ```
#
# The block short-hand syntax can be used here.
# It will reference the current subject.
#
# ```
# expect { subject << :foo }.to change(&.size).by(1)
# ```
macro change(&expression)
{% if expression.is_a?(Nop) %}
{% raise "Block must be provided to change matcher" %}
{% end %}
# Check if the short-hand method syntax is used.
# This is a hack, since macros don't get this as a "literal" or something similar.
# The Crystal compiler will translate:
# ```
# &.foo
# ```
# to:
# ```
# { |__arg0| __arg0.foo }
# ```
# The hack used here is to check if it looks like a compiler-generated block.
{% if expression.args == ["__arg0".id] && expression.body.is_a?(Call) && expression.body.id =~ /^__arg0\./ %}
# Extract the method name to make it clear to the user what is tested.
# The raw block can't be used because it's not clear to the user.
{% method_name = expression.body.id.split('.')[1..-1].join('.') %}
%proc = ->{ subject.{{method_name.id}} }
%test_block = ::Spectator::TestBlock.create(%proc, {{"#" + method_name}})
{% elsif expression.args.empty? %}
# In this case, it looks like the short-hand method syntax wasn't used.
# Capture the block as a proc and pass along.
%proc = ->{{expression}}
%test_block = ::Spectator::TestBlock.create(%proc, {{"`" + expression.body.stringify + "`"}})
{% else %}
{% raise "Unexpected block arguments in change matcher" %}
{% end %}
::Spectator::Matchers::ChangeMatcher.new(%test_block)
end
# Indicates that some block should raise an error.
@ -622,7 +711,8 @@ module Spectator::DSL
{% end %}
label << ')'
{% end %}
::Spectator::Matchers::{{matcher.id}}.new(::Spectator::TestValue.new(descriptor, label.to_s))
test_value = ::Spectator::TestValue.new(descriptor, label.to_s)
::Spectator::Matchers::{{matcher.id}}.new(test_value)
end
end
end

84
src/spectator/matchers/change_exact_matcher.cr Normal file
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@ -0,0 +1,84 @@
require "./failed_match_data"
require "./matcher"
require "./successful_match_data"
module Spectator::Matchers
# Matcher that tests whether an expression changed from and to specific values.
struct ChangeExactMatcher(ExpressionType, FromType, ToType) < Matcher
# The expression that is expected to (not) change.
private getter expression
# The expected value of the expression before the change.
private getter expected_before
# The expected value of the expression after the change.
private getter expected_after
# Creates a new change matcher.
def initialize(@expression : TestBlock(ExpressionType), @expected_before : FromType, @expected_after : ToType)
end
# Short text about the matcher's purpose.
# This explains what condition satisfies the matcher.
# The description is used when the one-liner syntax is used.
def description
"changes #{expression.label} from #{expected_before.inspect} to #{expected_after.inspect}"
end
# Actually performs the test against the expression.
def match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if expected_before == before
if before == after
FailedMatchData.new("#{actual.label} did not change #{expression.label}",
before: before.inspect,
after: after.inspect
)
elsif expected_after == after
SuccessfulMatchData.new
else
FailedMatchData.new("#{actual.label} did not change #{expression.label} to #{expected_after.inspect}",
before: before.inspect,
after: after.inspect,
expected: expected_after.inspect
)
end
else
FailedMatchData.new("#{expression.label} was not initially #{expected_before.inspect}",
expected: expected_before.inspect,
actual: before.inspect,
)
end
end
# Performs the test against the expression, but inverted.
# A successful match with `#match` should normally fail for this method, and vice-versa.
def negated_match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if expected_before == before
if expected_after == after
FailedMatchData.new("#{actual.label} changed #{expression.label} from #{expected_before.inspect} to #{expected_after.inspect}",
before: before.inspect,
after: after.inspect
)
else
SuccessfulMatchData.new
end
else
FailedMatchData.new("#{expression.label} was not initially #{expected_before.inspect}",
expected: expected_before.inspect,
actual: before.inspect,
)
end
end
# Performs the change and reports the before and after values.
private def change(actual)
before = expression.value # Retrieve the expression's initial value.
actual.value # Invoke action that might change the expression's value.
after = expression.value # Retrieve the expression's value again.
{before, after}
end
end
end

84
src/spectator/matchers/change_from_matcher.cr Normal file
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@ -0,0 +1,84 @@
require "./change_exact_matcher"
require "./failed_match_data"
require "./matcher"
require "./successful_match_data"
module Spectator::Matchers
# Matcher that tests whether an expression changed from a specific value.
struct ChangeFromMatcher(ExpressionType, FromType) < Matcher
# The expression that is expected to (not) change.
private getter expression
# The expected value of the expression before the change.
private getter expected
# Creates a new change matcher.
def initialize(@expression : TestBlock(ExpressionType), @expected : FromType)
end
# Short text about the matcher's purpose.
# This explains what condition satisfies the matcher.
# The description is used when the one-liner syntax is used.
def description
"changes #{expression.label} from #{expected}"
end
# Actually performs the test against the expression.
def match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if expected != before
FailedMatchData.new("#{expression.label} was not initially #{expected}",
expected: expected.inspect,
actual: before.inspect,
)
elsif before == after
FailedMatchData.new("#{actual.label} did not change #{expression.label} from #{expected}",
before: before.inspect,
after: after.inspect,
expected: "Not #{expected.inspect}"
)
else
SuccessfulMatchData.new
end
end
# Performs the test against the expression, but inverted.
# A successful match with `#match` should normally fail for this method, and vice-versa.
def negated_match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if expected != before
FailedMatchData.new("#{expression.label} was not initially #{expected}",
expected: expected.inspect,
actual: before.inspect
)
elsif before == after
SuccessfulMatchData.new
else
FailedMatchData.new("#{actual.label} changed #{expression.label} from #{expected}",
before: before.inspect,
after: after.inspect,
expected: expected.inspect
)
end
end
# Specifies what the resulting value of the expression must be.
def to(value : T) forall T
ChangeExactMatcher.new(@expression, @expected, value)
end
# Specifies what the resulting value of the expression should change by.
def by(amount : T) forall T
ChangeExactMatcher.new(@expression, @expected, @expected + value)
end
# Performs the change and reports the before and after values.
private def change(actual)
before = expression.value # Retrieve the expression's initial value.
actual.value # Invoke action that might change the expression's value.
after = expression.value # Retrieve the expression's value again.
{before, after}
end
end
end

85
src/spectator/matchers/change_matcher.cr Normal file
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@ -0,0 +1,85 @@
require "./change_from_matcher"
require "./change_to_matcher"
require "./failed_match_data"
require "./matcher"
require "./successful_match_data"
module Spectator::Matchers
# Matcher that tests whether an expression changed.
struct ChangeMatcher(ExpressionType) < Matcher
# The expression that is expected to (not) change.
private getter expression
# Creates a new change matcher.
def initialize(@expression : TestBlock(ExpressionType))
end
# Short text about the matcher's purpose.
# This explains what condition satisfies the matcher.
# The description is used when the one-liner syntax is used.
def description
"changes #{expression.label}"
end
# Actually performs the test against the expression.
def match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if before == after
FailedMatchData.new("#{actual.label} did not change #{expression.label}",
before: before.inspect,
after: after.inspect
)
else
SuccessfulMatchData.new
end
end
# Performs the test against the expression, but inverted.
# A successful match with `#match` should normally fail for this method, and vice-versa.
def negated_match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if before == after
SuccessfulMatchData.new
else
FailedMatchData.new("#{actual.label} changed #{expression.label}",
before: before.inspect,
after: after.inspect
)
end
end
# Specifies what the initial value of the expression must be.
def from(value : T) forall T
ChangeFromMatcher.new(@expression, value)
end
# Specifies what the resulting value of the expression must be.
def to(value : T) forall T
ChangeToMatcher.new(@expression, value)
end
# Specifies that t he resulting value must be some amount different.
def by(amount : T) forall T
ChangeRelativeMatcher.new(@expression, "by #{amount}") { |before, after| amount == after - before }
end
# Specifies that the resulting value must be at least some amount different.
def by_at_least(minimum : T) forall T
ChangeRelativeMatcher.new(@expression, "by at least #{minimum}") { |before, after| minimum <= after - before }
end
# Specifies that the resulting value must be at most some amount different.
def by_at_most(maximum : T) forall T
ChangeRelativeMatcher.new(@expression, "by at most #{maximum}") { |before, after| maximum >= after - before }
end
# Performs the change and reports the before and after values.
private def change(actual)
before = expression.value # Retrieve the expression's initial value.
actual.value # Invoke action that might change the expression's value.
after = expression.value # Retrieve the expression's value again.
{before, after}
end
end
end

57
src/spectator/matchers/change_relative_matcher.cr Normal file
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@ -0,0 +1,57 @@
require "./failed_match_data"
require "./matcher"
require "./successful_match_data"
module Spectator::Matchers
# Matcher that tests whether an expression changed by an amount.
struct ChangeRelativeMatcher(ExpressionType) < Matcher
# The expression that is expected to (not) change.
private getter expression
# Creates a new change matcher.
def initialize(@expression : TestBlock(ExpressionType), @relativity : String,
&evaluator : ExpressionType, ExpressionType -> Bool)
@evaluator = evaluator
end
# Short text about the matcher's purpose.
# This explains what condition satisfies the matcher.
# The description is used when the one-liner syntax is used.
def description
"changes #{expression.label} #{@relativity}"
end
# Actually performs the test against the expression.
def match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if before == after
FailedMatchData.new("#{actual.label} did not change #{expression.label}",
before: before.inspect,
after: after.inspect
)
elsif @evaluator.call(before, after)
SuccessfulMatchData.new
else
FailedMatchData.new("#{actual.label} did not change #{expression.label} #{@relativity}",
before: before.inspect,
after: after.inspect
)
end
end
# Performs the test against the expression, but inverted.
# A successful match with `#match` should normally fail for this method, and vice-versa.
def negated_match(actual : TestExpression(T)) : MatchData forall T
{% raise "The `expect { }.to_not change { }.by_...()` syntax is not supported (ambiguous)." %}
end
# Performs the change and reports the before and after values.
private def change(actual)
before = expression.value # Retrieve the expression's initial value.
actual.value # Invoke action that might change the expression's value.
after = expression.value # Retrieve the expression's value again.
{before, after}
end
end
end

78
src/spectator/matchers/change_to_matcher.cr Normal file
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@ -0,0 +1,78 @@
require "./change_exact_matcher"
require "./failed_match_data"
require "./matcher"
require "./successful_match_data"
module Spectator::Matchers
# Matcher that tests whether an expression changed to a specific value.
struct ChangeToMatcher(ExpressionType, ToType) < Matcher
# The expression that is expected to (not) change.
private getter expression
# The expected value of the expression after the change.
private getter expected
# Creates a new change matcher.
def initialize(@expression : TestBlock(ExpressionType), @expected : ToType)
end
# Short text about the matcher's purpose.
# This explains what condition satisfies the matcher.
# The description is used when the one-liner syntax is used.
def description
"changes #{expression.label} to #{expected}"
end
# Actually performs the test against the expression.
def match(actual : TestExpression(T)) : MatchData forall T
before, after = change(actual)
if before == after
FailedMatchData.new("#{actual.label} did not change #{expression.label}",
before: before.inspect,
after: after.inspect,
expected: expected.inspect
)
elsif expected == after
SuccessfulMatchData.new
else
FailedMatchData.new("#{actual.label} did not change #{expression.label} to #{expected}",
before: before.inspect,
after: after.inspect,
expected: expected.inspect
)
end
end
# Negated matching for this matcher is not supported.
# Attempting to call this method will result in a compilation error.
#
# This syntax has a logical problem.
# "The action does not change the expression to some value."
# Is it a failure if the value is not changed,
# but it is the expected value?
#
# RSpec doesn't support this syntax either.
def negated_match(actual : TestExpression(T)) : MatchData forall T
{% raise "The `expect { }.to_not change { }.to()` syntax is not supported (ambiguous)." %}
end
# Specifies what the initial value of the expression must be.
def from(value : T) forall T
ChangeExactMatcher.new(@expression, value, @expected)
end
# Specifies how much the initial value should change by.
def by(amount : T) forall T
ChangeExactMatcher.new(@expression, @expected - amount, @expected)
end
# Performs the change and reports the before and after values.
private def change(actual)
before = expression.value # Retrieve the expression's initial value.
actual.value # Invoke action that might change the expression's value.
after = expression.value # Retrieve the expression's value again.
{before, after}
end
end
end