Add docs to expectations methods (#5092)

* Add docs to expectations methods * improve wording and example code for `be` matchers * Add documentation to other Spec methods * Improve wording in spec preface
crystal-lang · Oct 26, 2017 · 844cc6e · 844cc6e
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diff --git a/src/spec.cr b/src/spec.cr
@@ -1,13 +1,16 @@
 require "./spec/dsl"
 
-# Crystal's built-in testing library.
+# 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 Array do
 #   describe "#size" do
 #     it "correctly reports the number of elements in the Array" do
 #       [1, 2, 3].size.should eq 3
@@ -45,21 +48,19 @@ require "./spec/dsl"
 # 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:
+# and run the specs of a project by running `crystal spec`.
 #
 # ```shell
+# # Run  all specs in files matching spec/**/*_spec.cr
 # crystal spec
-# ```
 #
-# You can also compile and run individual spec files by providing their path:
+# # Run all specs in files matching spec/my/test/**/*_spec.cr
+# crystal spec spec/my/test/
 #
-# ```shell
+# # Run all specs in spec/my/test/file_spec.cr
 # crystal spec spec/my/test/file_spec.cr
-# ```
-#
-# In addition, you may run individual specs by providing a line number:
 #
-# ```shell
+# # 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
 # ```
 module Spec

diff --git a/src/spec/expectations.cr b/src/spec/expectations.cr
@@ -200,62 +200,92 @@ module Spec
     end
   end
 
+  # This module defines a number of methods to create expectations, which are
+  # automatically included into the top level namespace.
+  #
+  # Expectations are used by `Spec::ObjectExtensions#should` and `Spec::ObjectExtensions#should_not`.
   module Expectations
+    # Creates an `Expectation` that passes if actual equals *value* (`==`).
     def eq(value)
       Spec::EqualExpectation.new value
     end
 
+    # Creates an `Expectation` that passes if actual and *value* are identical (`.same?`).
     def be(value)
       Spec::BeExpectation.new value
     end
 
+    # Creates an `Expectation` that passes if actual is true (`== true`).
     def be_true
       eq true
     end
 
+    # Creates an `Expectation` that passes if actual is false (`== false`).
     def be_false
       eq false
     end
 
+    # Creates an `Expectation` that passes if actual is truthy (neither `nil` nor `false`).
     def be_truthy
       Spec::BeTruthyExpectation.new
     end
 
+    # Creates an `Expectation` that passes if actual is falsy (`nil` or `false`).
     def be_falsey
       Spec::BeFalseyExpectation.new
     end
 
+    # Creates an `Expectation` that passes if actual is nil (`== nil`).
     def be_nil
       Spec::BeNilExpectation.new
     end
 
+    # Creates an `Expectation` that passes if actual is within *delta* of *expected*.
     def be_close(expected, delta)
       Spec::CloseExpectation.new(expected, delta)
     end
 
+    # Returns a factory to create a comparison `Expectation` that:
+    #
+    # * passes if actual is lesser than *value*: `be < value`
+    # * passes if actual is lesser than or equal *value*: `be <= value`
+    # * passes if actual is greater than *value*: `be > value`
+    # * passes if actual is greater than or equal *value*: `be >= value`
     def be
       Spec::Be
     end
 
+    # Creates an `Expectation` that passes if actual matches *value* (`=~`).
     def match(value)
       Spec::MatchExpectation.new(value)
     end
 
-    # Passes if actual includes *expected*. Works on collections and `String`.
+    # Creates an `Expectation` that  passes if actual includes *expected* (`.includes?`).
+    # Works on collections and `String`.
     def contain(expected)
       Spec::ContainExpectation.new(expected)
     end
 
+    # Creates an `Expectation` that passes if actual is of type *type* (`is_a?`).
     macro be_a(type)
       Spec::BeAExpectation({{type}}).new
     end
 
+    # Runs the block and passes if it raises an exception of type *klass*.
+    #
+    # It returns the rescued exception.
     macro expect_raises(klass)
       expect_raises({{klass}}, nil) do
         {{yield}}
       end
     end
 
+    # Runs the block and passes if it raises an exception of type *klass* and the error message matches.
+    #
+    # If *message* is a string, it matches if the exception's error message contains that string.
+    # If *message* is a regular expression, it is used to match the error message.
+    #
+    # It returns the rescued exception.
     macro expect_raises(klass, message, file = __FILE__, line = __LINE__)
       %failed = false
       begin
@@ -297,12 +327,18 @@ module Spec
   end
 
   module ObjectExtensions
+    # Validates an expectation and fails the example if it does not match.
+    #
+    # See `Spec::Expecations` for available expectations.
     def should(expectation, file = __FILE__, line = __LINE__)
       unless expectation.match self
         fail(expectation.failure_message(self), file, line)
       end
     end
 
+    # Validates an expectation and fails the example if it matches.
+    #
+    # See `Spec::Expecations` for available expectations.
     def should_not(expectation, file = __FILE__, line = __LINE__)
       if expectation.match self
         fail(expectation.negative_failure_message(self), file, line)

diff --git a/src/spec/methods.cr b/src/spec/methods.cr
@@ -1,12 +1,40 @@
 module Spec::Methods
+  # Defines an example group that describes a unit to be tested.
+  # Inside *&block* examples are defined by `#it` or `#pending`.
+  #
+  # Several `describe` blocks can be nested.
+  #
+  # Example:
+  # ```
+  # describe "Int32" do
+  #   describe "+" do
+  #     it "adds" { (1 + 1).should eq 2 }
+  #   end
+  # end
+  # ```
   def describe(description, file = __FILE__, line = __LINE__, &block)
     Spec::RootContext.describe(description.to_s, file, line, &block)
   end
 
+  # Defines an example group that establishes a specifc context,
+  # like *empty array* versus *array with elements*.
+  # Inside *&block* examples are defined by `#it` or `#pending`.
+  #
+  # It is functionally equivalent to `#describe`.
   def context(description, file = __FILE__, line = __LINE__, &block)
     describe(description.to_s, file, line, &block)
   end
 
+  # Defines a concrete test case.
+  #
+  # The test is performed by the block supplied to *&block*.
+  #
+  # Example:
+  # ```
+  # it "adds" { (1 + 1).should eq 2 }
+  # ```
+  #
+  # It is usually used inside a `#describe` or `#context` section.
   def it(description = "assert", file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
     return unless Spec.matches?(description, file, line, end_line)
 
@@ -28,6 +56,17 @@ module Spec::Methods
     end
   end
 
+  # Defines a pending test case.
+  #
+  # *&block* is never evaluated.
+  # It can be used to describe behaviour that is not yet implemented.
+  #
+  # Example:
+  # ```
+  # pending "check cat" { cat.alive? }
+  # ```
+  #
+  # It is usually used inside a `#describe` or `#context` section.
   def pending(description = "assert", file = __FILE__, line = __LINE__, end_line = __END_LINE__, &block)
     return unless Spec.matches?(description, file, line, end_line)
 
@@ -41,6 +80,9 @@ module Spec::Methods
     {{ raise "'assert' was removed: use 'it' instead".id }}
   end
 
+  # Fails an example.
+  #
+  # This method can be used to manually fail an example defined in an `#it` block.
   def fail(msg, file = __FILE__, line = __LINE__)
     raise Spec::AssertionFailed.new(msg, file, line)
   end