Use Nix flake for development (#17)

* Clarify CI role with the name

* Use Nix flake

* Avoid to depend own dependent config as the test fixture

.envrc

@@ -1 +1 @@
-use_nix
+use flake

.github/workflows/ci-dev.yml → .github/workflows/ci-nix.yml

@@ -1,15 +1,17 @@
-name: CI - Development Environment
+name: CI - Nix
 on:
   push:
     branches: [main]
     paths:
-      - '.github/workflows/ci-dev.yml'
+      - '.github/workflows/ci-nix.yml'
       - '*.nix'
+      - 'flake.*'
       - 'Taskfile.yml'
   pull_request:
     paths:
-      - '.github/workflows/ci-dev.yml'
+      - '.github/workflows/ci-nix.yml'
       - '*.nix'
+      - 'flake.*'
       - 'Taskfile.yml'
   schedule:
     # Every 10:42 JST
@@ -25,8 +27,9 @@ jobs:
       - uses: actions/checkout@v3
       - uses: DeterminateSystems/nix-installer-action@v4
       - uses: DeterminateSystems/magic-nix-cache-action@v2
-      - run: nix-build
-      - name: Log current versions
-        run: nix-shell --run 'task versions'
-      - name: Run main task
-        run: nix-shell --run 'task'
+      - name: Print nixpkgs version
+        run: nix-instantiate --eval -E '(import <nixpkgs> {}).lib.version'
+      - run: nix flake check
+      - run: nix develop --command echo 'This step should be done before any other "nix develop" steps because of measuring Nix build time'
+      - run: nix develop --command task versions
+      - run: nix develop --command task

.gitignore

@@ -25,3 +25,5 @@ go.work
 
 # goreleaser generates to
 dist/
+
+.direnv/

CONTRIBUTING.md

@@ -3,12 +3,12 @@
 ## Setup
 
 1. Install [Nix](https://nixos.org/) package manager
-2. Run `nix-shell` or `nix-shell --command 'zsh'`
+2. Run `nix develop` or `direnv allow` in project root
 3. You can use development tools
 
 ```console
-> nix-shell
-(prepared bash)
+> nix develop
+(prepared shell)
 
 > task fmt
 task: [fmt] dprint fmt

core_test.go

@@ -1,8 +1,26 @@
 package core
 
-import "testing"
+import (
+	"os"
+	"testing"
+)
 
 func TestGetCurrentVersion(t *testing.T) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("failed to get current working directory: %v", err)
+	}
+	t.Cleanup(func() {
+		err := os.Chdir(cwd)
+		if err != nil {
+			t.Fatalf("failed to rollback working directory: %v", err)
+		}
+	})
+	err = os.Chdir("testdata")
+	if err != nil {
+		t.Fatalf("failed to walk through testdata directory: %v", err)
+	}
+
 	got, err := GetCurrentVersion("default.nix")
 	if err != nil {
 		t.Fatalf("Getting the version has been failed: %s", err.Error())
@@ -28,6 +46,21 @@ func TestGetLastVersion(t *testing.T) {
 }
 
 func TestTargetPath(t *testing.T) {
+	cwd, err := os.Getwd()
+	if err != nil {
+		t.Fatalf("failed to get current working directory: %v", err)
+	}
+	t.Cleanup(func() {
+		err := os.Chdir(cwd)
+		if err != nil {
+			t.Fatalf("failed to rollback working directory: %v", err)
+		}
+	})
+	err = os.Chdir("testdata")
+	if err != nil {
+		t.Fatalf("failed to walk through testdata directory: %v", err)
+	}
+
 	got, err := GetTargetPath()
 	if err != nil {
 		t.Fatalf("Failed to get target files: %s", err.Error())

flake.nix

@@ -0,0 +1,27 @@
+{
+  inputs = {
+    nixpkgs.url = "github:NixOS/nixpkgs/e57b65abbbf7a2d5786acc86fdf56cde060ed026";
+    flake-utils.url = "github:numtide/flake-utils";
+  };
+
+  outputs = { self, nixpkgs, flake-utils }:
+    flake-utils.lib.eachDefaultSystem (system:
+      let
+        pkgs = nixpkgs.legacyPackages.${system};
+      in
+      {
+        devShells.default = with pkgs;
+          mkShell {
+            buildInputs = [
+              go_1_20
+              nil
+              nixpkgs-fmt
+              dprint
+              actionlint
+              go-task
+              goreleaser
+              typos
+            ];
+          };
+      });
+}

default.nix → testdata/default.nix

@@ -3,12 +3,7 @@
 pkgs.mkShell {
   buildInputs = [
     pkgs.go_1_20
-    pkgs.nil
-    pkgs.nixpkgs-fmt
-    pkgs.dprint
-    pkgs.actionlint
     pkgs.go-task
     pkgs.goreleaser
-    pkgs.typos
   ];
 }