Add Test Suite and Library (#30)

* added library and test scaffoding

* Add bin/test

* Update comments

Co-authored-by: Sridhar Ratnakumar <srid@srid.ca>

.ghcid

@@ -1 +0,0 @@
---warnings -T ":main"

README.md

@@ -6,7 +6,7 @@ Get a Haskell development environment up and running quickly, as long as Nix is
 
 This repository is a Haskell project template that is optimized for a fully reproducible and friendly development environment. It is based on:
 
-- [Nix](http://www.srid.ca/haskell-nix) + [Flakes](https://serokell.io/blog/practical-nix-flakes) (via [`github:srid/haskell-flake`](https://github.com/srid/haskell-flake)) + GHC 9
+- [Nix](https://srid.ca/haskell-nix) + [Flakes](https://serokell.io/blog/practical-nix-flakes) (via [`github:srid/haskell-flake`](https://github.com/srid/haskell-flake)) + GHC 9
 - VSCode + [HLS](https://github.com/haskell/haskell-language-server)
 - [fourmolu](https://github.com/fourmolu/fourmolu) autoformatting 
 - [Relude](https://github.com/kowainik/relude#relude) as Prelude.
@@ -49,6 +49,7 @@ git add . && git commit -m rename
 - Run `nix flake update` to update all flake inputs.
 - Run `treefmt` in nix shell to autoformat the project. This uses [treefmt](https://github.com/numtide/treefmt), which uses `./treefmt.toml` (where fourmolu and nixpkgs-fmt are specified).
 - Run `bin/hoogle` to start Hoogle with packages in your cabal file.
+- Run `bin/test` to run the test suite.
 - Run the application without installing: `nix run github:srid/haskell-template` (or `nix run .` from checkout)
 
 ## Alternatives

bin/run

@@ -1,8 +1,4 @@
 #!/usr/bin/env bash
 set -xe
 
-# This will run ghcid, which uses `./.ghcid` to invoke your program main entry
-# point, with the specified args.
-#
-# If you change ./.ghcid, ghcid will automatically reload.
-exec nix develop -c ghcid
+exec nix develop -c ghcid -c "cabal repl exe:haskell-template" --warnings -T :main

bin/test

@@ -0,0 +1,4 @@
+#!/usr/bin/env bash
+set -xe
+
+exec nix develop -c ghcid -c "cabal repl test:tests"

haskell-template.cabal

@@ -21,35 +21,17 @@ extra-source-files:
   LICENSE
   README.md
 
-executable haskell-template
-  build-depends:
-    , aeson
-    , async
-    , base          >=4.13.0.0 && <=4.18.0.0
-    , bytestring
-    , containers
-    , data-default
-    , directory
-    , filepath
-    , mtl
-    , optics-core
-    , profunctors
-    , relude
-    , shower
-    , text
-    , time
-    , with-utf8
+common shared
+  ghc-options:
+    -Wall -Wincomplete-record-updates -Wincomplete-uni-patterns
+    -Wmissing-deriving-strategies -Wunused-foralls -Wunused-foralls
+    -fprint-explicit-foralls -fprint-explicit-kinds
 
   mixins:
     base hiding (Prelude),
     relude (Relude as Prelude, Relude.Container.One),
     relude
 
-  ghc-options:
-    -Wall -Wincomplete-record-updates -Wincomplete-uni-patterns
-    -Wmissing-deriving-strategies -Wunused-foralls -Wunused-foralls
-    -fprint-explicit-foralls -fprint-explicit-kinds
-
   default-extensions:
     NoStarIsType
     BangPatterns
@@ -91,6 +73,41 @@ executable haskell-template
     TypeOperators
     ViewPatterns
 
-  main-is:            Main.hs
-  hs-source-dirs:     src
-  default-language:   Haskell2010
+  build-depends:
+    , aeson
+    , async
+    , base          >=4.13.0.0 && <=4.18.0.0
+    , bytestring
+    , containers
+    , data-default
+    , directory
+    , filepath
+    , mtl
+    , optics-core
+    , profunctors
+    , relude
+    , shower
+    , text
+    , time
+    , with-utf8
+
+executable haskell-template
+  import:           shared
+  main-is:          Main.hs
+  hs-source-dirs:   src
+  default-language: Haskell2010
+  other-modules:    Lib
+
+library
+  import:          shared
+  exposed-modules: Lib
+  hs-source-dirs:  src
+
+test-suite tests
+  import:         shared
+  main-is:        Main.hs
+  type:           exitcode-stdio-1.0
+  hs-source-dirs: tests
+  build-depends:
+    , haskell-template
+    , hspec

src/Lib.hs

@@ -0,0 +1,4 @@
+module Lib (hello) where
+
+hello :: Text
+hello = "Hello 🌎"

src/Main.hs

@@ -1,15 +1,15 @@
 module Main where
 
+import Lib qualified
 import Main.Utf8 qualified as Utf8
 
 {- |
  Main entry point.
 
- The `bin/run` script will invoke this function. See `.ghcid` file to change
- that.
+ The `bin/run` script will invoke this function.
 -}
 main :: IO ()
 main = do
   -- For withUtf8, see https://serokell.io/blog/haskell-with-utf8
   Utf8.withUtf8 $ do
-    putStrLn "Hello 🌎"
+    putTextLn Lib.hello

tests/Main.hs

@@ -0,0 +1,10 @@
+module Main where
+
+import Lib qualified
+import Test.Hspec (describe, hspec, it, shouldContain)
+
+main :: IO ()
+main = hspec $ do
+  describe "Lib.hello" $ do
+    it "contains the world emoji" $ do
+      toString Lib.hello `shouldContain` "🌎"