Crystal's built-in testing library. It provides a structure for writing executable examples of how your code should behave. A domain specific language allows you to write them in a way similar to natural language.
The Crystal compiler has a spec
command with tools to constrain which examples get run and tailor the output.
A basic spec looks something like this:
require "spec" describe Array do describe "#size" do it "correctly reports the number of elements in the Array" do [1, 2, 3].size.should eq 3 end end describe "#empty?" do it "is empty when no elements are in the array" do ([] of Int32).empty?.should be_true end it "is not empty if there are elements in the array" do [1].empty?.should be_false end end # lots more specs end
Test files are structured by use of the describe
or context
methods. Typically a top level describe
defines the outer
unit (such as a class) that is to be tested by the spec. Further describe
calls can be nested within the outer unit to specify smaller units under test (such as individual methods). describe
can also be used to set up a certain context - think empty Array
versus Array
with elements. The context
method behaves just like the describe
method and may be used instead, to emphasize context to the reader.
Within a describe
block, concrete test cases are defined with it
. A descriptive string is supplied to it
describing what the test case tests specifically.
Specs then use the should
method to verify that the expected value is returned. See the example above for details.
By convention, specs live in the spec
directory of a project. You can compile and run the specs of a project by running crystal spec
.
# Run all specs in files matching spec/**/*_spec.cr crystal spec # Run all specs in files matching spec/my/test/**/*_spec.cr crystal spec spec/my/test/ # Run all specs in spec/my/test/file_spec.cr crystal spec spec/my/test/file_spec.cr # Run the spec or group defined in line 14 of spec/my/test/file_spec.cr crystal spec spec/my/test/file_spec.cr:14 # Run all specs tagged with "fast" crystal spec --tag 'fast' # Run all specs not tagged with "slow" crystal spec --tag '~slow'
A describe
, context
or it
can be marked with focus: true
, like this:
it "adds", focus: true do (2 + 2).should_not eq(5) end
If any such thing is marked with focus: true
then only those examples will run.
Specs, by default, run in the order defined, but can be run in a random order by passing --order random
to crystal spec
.
Specs run in random order will display a seed value upon completion. This seed value can be used to rerun the specs in that same order by passing the seed value to --order
.
Instructs the spec runner to execute the given block after each spec spec in the spec suite.
Instructs the spec runner to execute the given block after the entire spec suite.
Instructs the spec runner to execute the given block when each spec in the spec suite runs.
Instructs the spec runner to execute the given block before each spec in the spec suite.
Instructs the spec runner to execute the given block before the entire spec suite.
Instructs the spec runner to execute the given block after each spec spec in the spec suite.
If multiple blocks are registered they run in the reversed order that they are given.
For example:
Spec.after_each { puts 1 } Spec.after_each { puts 2 }
will print, just after each spec, 2 and then 1.
Instructs the spec runner to execute the given block after the entire spec suite.
If multiple blocks are registered they run in the reversed order that they are given.
For example:
Spec.after_suite { puts 1 } Spec.after_suite { puts 2 }
will print, just after the spec suite ends, 2 and then 1.
Instructs the spec runner to execute the given block when each spec in the spec suite runs.
The block must call run
on the given Example::Procsy
object.
If multiple blocks are registered they run in the reversed order that they are given.
require "spec" Spec.around_each do |example| puts "runs before each sample" example.run puts "runs after each sample" end it { } it { }
Instructs the spec runner to execute the given block before each spec in the spec suite.
If multiple blocks are registered they run in the order that they are given.
For example:
Spec.before_each { puts 1 } Spec.before_each { puts 2 }
will print, just before each spec, 1 and then 2.
Instructs the spec runner to execute the given block before the entire spec suite.
If multiple blocks are registered they run in the order that they are given.
For example:
Spec.before_suite { puts 1 } Spec.before_suite { puts 2 }
will print, just before the spec suite starts, 1 and then 2.
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Licensed under the Apache License, Version 2.0.
https://crystal-lang.org/api/0.35.1/Spec.html