Convert to use hedgehog and hspec

[newhoggy]

Test with:

cabal v2-test --enable-tests --write-ghc-environment-files=ghc8.4.4+ --test-show-details=direct

[newhoggy]

Also fixes the following warnings:

Data/RTree/Strict.hs:68:1: warning: [-Wunused-imports]
    The import of ‘Data.Semigroup’ is redundant
      except perhaps to import instances from ‘Data.Semigroup’
    To import instances alone, use: import Data.Semigroup()
   |
68 | import           Data.Semigroup
   | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

test/RTreeStrict.hs:158:1: warning: [-Worphans]
    Orphan instance: instance Arbitrary MBB
    To avoid this
        move the instance declaration to the module of the class or of the type, or
        wrap the type with a newtype and declare the instance on the new type.
    |
158 | instance QA.Arbitrary MBB where
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

test/RTreeProperties.hs:281:1: warning: [-Worphans]
    Orphan instance: instance Arbitrary MBB
    To avoid this
        move the instance declaration to the module of the class or of the type, or
        wrap the type with a newtype and declare the instance on the new type.
    |
281 | instance Arbitrary MBB where
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

test/RTreeProperties.hs:295:1: warning: [-Worphans]
    Orphan instance: instance Arbitrary (RTree Int)
    To avoid this
        move the instance declaration to the module of the class or of the type, or
        wrap the type with a newtype and declare the instance on the new type.
    |
295 | instance Arbitrary (RTree Int) where
    | ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^...

[newhoggy]

I'm not sure why CI checks aren't showing up in my PRs.

But they are building: https://github.com/haskell-works/r-tree/commit/136da05f7be878f2a35805664df285e197b82f9d/checks?check_suite_id=415642824

[newhoggy]

That's better.

[sebastian-philipp]

Awesome! ❤️

[sebastian-philipp]

is there a tool you're using to format the code?

[newhoggy]

I'm set up to use stylish-haskell with Visual Studio Code.

Currently using these rules:

$ cat .stylish-haskell.yaml
# stylish-haskell configuration file
# ==================================

# The stylish-haskell tool is mainly configured by specifying steps. These steps
# are a list, so they have an order, and one specific step may appear more than
# once (if needed). Each file is processed by these steps in the given order.
steps:
  # Convert some ASCII sequences to their Unicode equivalents. This is disabled
  # by default.
  # - unicode_syntax:
  #     # In order to make this work, we also need to insert the UnicodeSyntax
  #     # language pragma. If this flag is set to true, we insert it when it's
  #     # not already present. You may want to disable it if you configure
  #     # language extensions using some other method than pragmas. Default:
  #     # true.
  #     add_language_pragma: true

  # Align the right hand side of some elements.  This is quite conservative
  # and only applies to statements where each element occupies a single
  # line.
  - simple_align:
      cases: true
      top_level_patterns: true
      records: true

  # Import cleanup
  - imports:
      # There are different ways we can align names and lists.
      #
      # - global: Align the import names and import list throughout the entire
      #   file.
      #
      # - file: Like global, but don't add padding when there are no qualified
      #   imports in the file.
      #
      # - group: Only align the imports per group (a group is formed by adjacent
      #   import lines).
      #
      # - none: Do not perform any alignment.
      #
      # Default: global.
      align: group

      # Folowing options affect only import list alignment.
      #
      # List align has following options:
      #
      # - after_alias: Import list is aligned with end of import including
      #   'as' and 'hiding' keywords.
      #
      #   > import qualified Data.List      as List (concat, foldl, foldr, head,
      #   >                                          init, last, length)
      #
      # - with_alias: Import list is aligned with start of alias or hiding.
      #
      #   > import qualified Data.List      as List (concat, foldl, foldr, head,
      #   >                                 init, last, length)
      #
      # - new_line: Import list starts always on new line.
      #
      #   > import qualified Data.List      as List
      #   >     (concat, foldl, foldr, head, init, last, length)
      #
      # Default: after_alias
      list_align: after_alias

      # Long list align style takes effect when import is too long. This is
      # determined by 'columns' setting.
      #
      # - inline: This option will put as much specs on same line as possible.
      #
      # - new_line: Import list will start on new line.
      #
      # - new_line_multiline: Import list will start on new line when it's
      #   short enough to fit to single line. Otherwise it'll be multiline.
      #
      # - multiline: One line per import list entry.
      #   Type with contructor list acts like single import.
      #
      #   > import qualified Data.Map as M
      #   >     ( empty
      #   >     , singleton
      #   >     , ...
      #   >     , delete
      #   >     )
      #
      # Default: inline
      long_list_align: inline

      # Align empty list (importing instances)
      #
      # Empty list align has following options
      #
      # - inherit: inherit list_align setting
      #
      # - right_after: () is right after the module name:
      #
      #   > import Vector.Instances ()
      #
      # Default: inherit
      empty_list_align: inherit

      # List padding determines indentation of import list on lines after import.
      # This option affects 'long_list_align'.
      #
      # - <integer>: constant value
      #
      # - module_name: align under start of module name.
      #   Useful for 'file' and 'group' align settings.
      list_padding: 4

      # Separate lists option affects formating of import list for type
      # or class. The only difference is single space between type and list
      # of constructors, selectors and class functions.
      #
      # - true: There is single space between Foldable type and list of it's
      #   functions.
      #
      #   > import Data.Foldable (Foldable (fold, foldl, foldMap))
      #
      # - false: There is no space between Foldable type and list of it's
      #   functions.
      #
      #   > import Data.Foldable (Foldable(fold, foldl, foldMap))
      #
      # Default: true
      separate_lists: true

  # Language pragmas
  - language_pragmas:
      # We can generate different styles of language pragma lists.
      #
      # - vertical: Vertical-spaced language pragmas, one per line.
      #
      # - compact: A more compact style.
      #
      # - compact_line: Similar to compact, but wrap each line with
      #   `{-#LANGUAGE #-}'.
      #
      # Default: vertical.
      style: vertical

      # Align affects alignment of closing pragma brackets.
      #
      # - true: Brackets are aligned in same collumn.
      #
      # - false: Brackets are not aligned together. There is only one space
      #   between actual import and closing bracket.
      #
      # Default: true
      align: true

      # stylish-haskell can detect redundancy of some language pragmas. If this
      # is set to true, it will remove those redundant pragmas. Default: true.
      remove_redundant: true

  # Replace tabs by spaces. This is disabled by default.
  # - tabs:
  #     # Number of spaces to use for each tab. Default: 8, as specified by the
  #     # Haskell report.
  #     spaces: 8

  # Remove trailing whitespace
  - trailing_whitespace: {}

# A common setting is the number of columns (parts of) code will be wrapped
# to. Different steps take this into account. Default: 80.
columns: 800

# By default, line endings are converted according to the OS. You can override
# preferred format here.
#
# - native: Native newline format. CRLF on Windows, LF on other OSes.
#
# - lf: Convert to LF ("\n").
#
# - crlf: Convert to CRLF ("\r\n").
#
# Default: native.
newline: native

# Sometimes, language extensions are specified in a cabal file or from the
# command line instead of using language pragmas in the file. stylish-haskell
# needs to be aware of these, so it can parse the file correctly.
#
# No language extensions are enabled by default.
# language_extensions:
  # - TemplateHaskell
  # - QuasiQuotes

[sebastian-philipp]

Please give me some time to have a look at hspec. At first, it looks to be a bit strange to have all the tests in one big main function. I need to get used to it!

[newhoggy]

It's possible to have them separate as well if you prefer or if you want to parameterise the test, although the support for working with tests when structured in the single function manner is very good.

For example you can change it to fit to make it the only test to run so you can concentrate on fixing a particular failing test. Or change it to xit to skip running that test.

[newhoggy]

One benefit of hedgehog is you get automatic shrinking for free. I supplied a custom shrinker here just in case you need that behaviour, but if you don't this can be dropped.

[newhoggy]

Another benefit of hedgehog is that the === operator will pretty print your data structures and do a diff so you can more easily see how your expected and actual values differ.