use github.com/spf13/cobra for app cmds

* add 'version' command - "go-xkcdreader version" returns a formatted
  version of the app
* test (among other things) that the version in flake.nix matches the
  version hardcoded in app's go code (cmd/version.go)

cmd/root.go

@@ -0,0 +1,35 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+// appName is the name of the app
+const appName = "go-xkcdreader"
+
+// Root is the main go-xkcdreader command
+var Root = &cobra.Command{
+	Use:   appName,
+	Short: "an offline-capable xkcd webcomic reader written in Go",
+	RunE: func(cmd *cobra.Command, args []string) error {
+		// the app will be started from here
+		// a noop atm
+		return nil
+	},
+}
+
+// GetAppName returns the name of the application
+func GetAppName() string {
+	return appName
+}
+
+// Execute is the entrypoint of cobra's poison
+func Execute() {
+	if err := Root.Execute(); err != nil {
+		fmt.Fprintln(os.Stderr, err)
+		os.Exit(1)
+	}
+}

cmd/root_test.go

@@ -0,0 +1,28 @@
+package cmd
+
+import (
+	"testing"
+)
+
+func TestGetAppName(t *testing.T) {
+	want := "go-xkcdreader"
+	got := GetAppName()
+
+	if got != want {
+		t.Errorf("App name strings don't match, want: %q', got: %q ", want, got)
+	}
+}
+
+func TestExecuteRootCmd(t *testing.T) {
+	rootcmd := *Root
+
+	err := rootcmd.Execute()
+	if err != nil {
+		t.Error("Failed to execute the root cmd")
+	}
+}
+
+// is this valid? dunno
+func TestExecuteFunc(t *testing.T) {
+	Execute()
+}

cmd/version.go

@@ -0,0 +1,47 @@
+package cmd
+
+import (
+	"fmt"
+	"os"
+
+	"github.com/spf13/cobra"
+)
+
+// version holds app version string
+var version = "v0.0.0"
+
+// used to determine whether to print short or long version string
+var shortVersion = false
+
+var cmdVersion = &cobra.Command{
+	Use:   "version",
+	Short: "Print version information and exit",
+	Long:  `All software has versions. This is ` + appName + `'s`,
+	RunE: func(cmd *cobra.Command, args []string) error {
+		fmt.Println(getVersion())
+		return nil
+	},
+	PersistentPostRun: func(cmd *cobra.Command, args []string) {
+		// exit with code 0 after showing the version
+		os.Exit(0)
+	},
+}
+
+// get (short if -s/--short flag is supplied) version
+func getVersion() string {
+	if !shortVersion {
+		return appName + " - " + version
+	}
+	return GetShortVersion()
+}
+
+// GetShortVersion returns a bare version string
+func GetShortVersion() string {
+	return version
+}
+
+// the init func registers the commands and flags with cobra
+func init() {
+	cmdVersion.Flags().BoolVarP(&shortVersion, "short", "s", false, "print just the version string and nothing else")
+	Root.AddCommand(cmdVersion)
+}

cmd/version_test.go

@@ -0,0 +1,66 @@
+package cmd
+
+import (
+	"bytes"
+	"os"
+	"regexp"
+	"testing"
+)
+
+func TestNixFlake_GosrcVersionStringEquivalence(t *testing.T) {
+	want := GetShortVersion()
+	fData, err := os.ReadFile("../flake.nix")
+
+	if err != nil {
+		t.Errorf("Failed to open flake.nix: %q", err)
+	}
+
+	got := bytes.Contains(fData, []byte("      version = \""+want+"\""))
+
+	if !got {
+		t.Errorf("Version string '%q' not found in ../flake.nix", want)
+	}
+}
+
+func TestVersionStringFormat(t *testing.T) {
+	v := version
+	// this expression matches the format of "vX.Y.Z" where {X,Y,Z} are digits
+	// (such as 0 or 123)
+	re := regexp.MustCompile(`^(v\d+\.\d+\.\d+)$`)
+	match := re.MatchString(v)
+
+	if !match {
+		t.Errorf("Incorrect version string format, must match regex: '%q', provided version string: '%q'", re.String(), v)
+	}
+}
+
+func TestGetVersion(t *testing.T) {
+	want := appName + " - " + version
+	got := getVersion()
+
+	if want != got {
+		t.Errorf("Incorrect version string, want: '%q', got: '%q'", want, got)
+	}
+}
+
+// set shortVersion variable manually
+func TestGetVersionWithShortVersionVar(t *testing.T) {
+	shortVersion = true
+	want := version
+
+	got := getVersion()
+
+	if want != got {
+		t.Errorf("Incorrect version string when 'shortVersion' is true, want: '%q', got: '%q'", want, got)
+	}
+}
+
+// explicitly get short version
+func TestGetShortVersion(t *testing.T) {
+	want := version
+	got := GetShortVersion()
+
+	if want != got {
+		t.Errorf("Incorrect 'short' version string, want: '%q', got: '%q'", want, got)
+	}
+}

flake.nix

@@ -69,13 +69,12 @@
             ldflags = [
               "-s"
               "-w"
-              "-X main.Version=${version}"
+              "-X cmd.version=${version}"
-              "-X main.Commit=${version}"
             ];
 
             modSha256 = lib.fakeSha256;
             # vendorSha256 = "";
-            vendorSha256 = "sha256-7ofcdvYLiAhR7bTyzcBMbyj3Sd8UIcGiFOOxgI87Yx8=";
+            vendorSha256 = "sha256-i6VOX1O/IqIOWUzgc/2U/a95KhzAG0/NOIG/D8E0BEk=";
 
             # In 'nix develop', we don't need a copy of the source tree
             # in the Nix store.
@@ -115,7 +114,7 @@
               name = "go-xkcdreader-" + version;
 
               GOFLAGS = "-buildmode=pie -trimpath -mod=readonly -modcacherw";
-              GOLDFLAGS = "-s -w -X main.Version=${version} -X main.Commit=${version}";
+              GOLDFLAGS = "-s -w -X cmd.version=${version}";
               CGO_CFLAGS = "-g2 -Og -mtune=generic";
               CGO_LDFLAGS = "-Wl,-O1,-sort-common,-as-needed,-z,relro,-z,now,-flto -pthread";
 

go.mod

@@ -2,7 +2,10 @@ module git.dotya.ml/wanderer/go-xkcdreader
 
 go 1.17
 
-require fyne.io/fyne/v2 v2.1.4
+require (
+	fyne.io/fyne/v2 v2.1.4
+	github.com/spf13/cobra v1.4.0
+)
 
 require (
 	github.com/davecgh/go-spew v1.1.1 // indirect
@@ -12,7 +15,9 @@ require (
 	github.com/go-gl/glfw/v3.3/glfw v0.0.0-20211024062804-40e447a793be // indirect
 	github.com/godbus/dbus/v5 v5.0.4 // indirect
 	github.com/goki/freetype v0.0.0-20181231101311-fa8a33aabaff // indirect
+	github.com/inconshreveable/mousetrap v1.0.0 // indirect
 	github.com/pmezard/go-difflib v1.0.0 // indirect
+	github.com/spf13/pflag v1.0.5 // indirect
 	github.com/srwiley/oksvg v0.0.0-20200311192757-870daf9aa564 // indirect
 	github.com/srwiley/rasterx v0.0.0-20200120212402-85cb7272f5e9 // indirect
 	github.com/stretchr/testify v1.5.1 // indirect
@@ -21,5 +26,5 @@ require (
 	golang.org/x/net v0.0.0-20210510120150-4163338589ed // indirect
 	golang.org/x/sys v0.0.0-20210630005230-0f9fa26af87c // indirect
 	golang.org/x/text v0.3.7 // indirect
-	gopkg.in/yaml.v2 v2.3.0 // indirect
+	gopkg.in/yaml.v2 v2.4.0 // indirect
 )

go.sum

@@ -5,6 +5,7 @@ github.com/BurntSushi/toml v0.4.1/go.mod h1:CxXYINrC8qIiEnFrOxCa7Jy5BFHlXnUU2pbi
 github.com/Kodeworks/golang-image-ico v0.0.0-20141118225523-73f0f4cfade9/go.mod h1:7uhhqiBaR4CpN0k9rMjOtjpcfGd6DG2m04zQxKnWQ0I=
 github.com/akavel/rsrc v0.8.0/go.mod h1:uLoCtb9J+EyAqh+26kdrTgmzRBFPGOolLWKpdxkKq+c=
 github.com/cpuguy83/go-md2man/v2 v2.0.0-20190314233015-f79a8a8ca69d/go.mod h1:maD7wRr/U5Z6m/iR4s+kqSMx2CaBsrgA7czyZG/E6dU=
+github.com/cpuguy83/go-md2man/v2 v2.0.1/go.mod h1:tgQtvFlXSQOSOSIRvRPT7W67SCa46tRHOmNcaadrF8o=
 github.com/davecgh/go-spew v1.1.0/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
 github.com/davecgh/go-spew v1.1.1 h1:vj9j/u1bqnvCEfJOwUhtlOARqs3+rkHYY13jYWTU97c=
 github.com/davecgh/go-spew v1.1.1/go.mod h1:J7Y8YcW2NihsgmVo/mv3lAwl/skON4iLHjSsI+c5H38=
@@ -21,6 +22,8 @@ github.com/godbus/dbus/v5 v5.0.4 h1:9349emZab16e7zQvpmsbtjc18ykshndd8y2PG3sgJbA=
 github.com/godbus/dbus/v5 v5.0.4/go.mod h1:xhWf0FNVPg57R7Z0UbKHbJfkEywrmjJnf7w5xrFpKfA=
 github.com/goki/freetype v0.0.0-20181231101311-fa8a33aabaff h1:W71vTCKoxtdXgnm1ECDFkfQnpdqAO00zzGXLA5yaEX8=
 github.com/goki/freetype v0.0.0-20181231101311-fa8a33aabaff/go.mod h1:wfqRWLHRBsRgkp5dmbG56SA0DmVtwrF5N3oPdI8t+Aw=
+github.com/inconshreveable/mousetrap v1.0.0 h1:Z8tu5sraLXCXIcARxBp/8cbvlwVa7Z1NHg9XEKhtSvM=
+github.com/inconshreveable/mousetrap v1.0.0/go.mod h1:PxqpIevigyE2G7u3NXJIT2ANytuPF1OarO4DADm73n8=
 github.com/jackmordaunt/icns v0.0.0-20181231085925-4f16af745526/go.mod h1:UQkeMHVoNcyXYq9otUupF7/h/2tmHlhrS2zw7ZVvUqc=
 github.com/josephspurrier/goversioninfo v0.0.0-20200309025242-14b0ab84c6ca/go.mod h1:eJTEwMjXb7kZ633hO3Ln9mBUCOjX2+FlTljvpl9SYdE=
 github.com/kr/pty v1.1.1/go.mod h1:pFQYn66WHrOpPYNljwOMqo10TkYh1fy3cYio2l3bCsQ=
@@ -35,9 +38,14 @@ github.com/pkg/errors v0.9.1/go.mod h1:bwawxfHBFNV+L2hUp1rHADufV3IMtnDRdf1r5NINE
 github.com/pmezard/go-difflib v1.0.0 h1:4DBwDE0NGyQoBHbLQYPwSUPoCMWR5BEzIk/f1lZbAQM=
 github.com/pmezard/go-difflib v1.0.0/go.mod h1:iKH77koFhYxTK1pcRnkKkqfTogsbg7gZNVY4sRDYZ/4=
 github.com/russross/blackfriday/v2 v2.0.1/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
+github.com/russross/blackfriday/v2 v2.1.0/go.mod h1:+Rmxgy9KzJVeS9/2gXHxylqXiyQDYRxCVz55jmeOWTM=
 github.com/shurcooL/sanitized_anchor_name v1.0.0/go.mod h1:1NzhyTcUVG4SuEtjjoZeVRXNmyL/1OwPU0+IJeTBvfc=
 github.com/spf13/afero v1.1.2/go.mod h1:j4pytiNVoe2o6bmDsKpLACNPDBIoEAkihy7loJ1B0CQ=
+github.com/spf13/cobra v1.4.0 h1:y+wJpx64xcgO1V+RcnwW0LEHxTKRi2ZDPSBjWnrg88Q=
+github.com/spf13/cobra v1.4.0/go.mod h1:Wo4iy3BUC+X2Fybo0PDqwJIv3dNRiZLHQymsfxlB84g=
 github.com/spf13/pflag v1.0.3/go.mod h1:DYY7MBk1bdzusC3SYhjObp+wFpr4gzcvqqNjLnInEg4=
+github.com/spf13/pflag v1.0.5 h1:iy+VFUOCP1a+8yFto/drg2CJ5u0yRoB7fZw3DKv/JXA=
+github.com/spf13/pflag v1.0.5/go.mod h1:McXfInJRrz4CZXVZOBLb0bTZqETkiAhM9Iw0y3An2Bg=
 github.com/srwiley/oksvg v0.0.0-20200311192757-870daf9aa564 h1:HunZiaEKNGVdhTRQOVpMmj5MQnGnv+e8uZNu3xFLgyM=
 github.com/srwiley/oksvg v0.0.0-20200311192757-870daf9aa564/go.mod h1:afMbS0qvv1m5tfENCwnOdZGOF8RGR/FsZ7bvBxQGZG4=
 github.com/srwiley/rasterx v0.0.0-20200120212402-85cb7272f5e9 h1:m59mIOBO4kfcNCEzJNy71UkeF4XIx2EVmL9KLwDQdmM=
@@ -91,5 +99,5 @@ gopkg.in/check.v1 v1.0.0-20200227125254-8fa46927fb4f/go.mod h1:Co6ibVJAznAaIkqp8
 gopkg.in/yaml.v2 v2.2.2/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.3/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
 gopkg.in/yaml.v2 v2.2.8/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
-gopkg.in/yaml.v2 v2.3.0 h1:clyUAQHOM3G0M3f5vQj7LuJrETvjVot3Z5el9nffUtU=
+gopkg.in/yaml.v2 v2.4.0 h1:D8xgwECY7CYvx+Y2n4sBz93Jn9JRvxdiyyo8CTfuKaY=
-gopkg.in/yaml.v2 v2.3.0/go.mod h1:hI93XBmqTisBFMUTm0b8Fm+jr3Dg1NNxqwp+5A1VGuI=
+gopkg.in/yaml.v2 v2.4.0/go.mod h1:RDklbk79AGWmwhnvt/jBztapEOGDOx6ZbXqjP6csGnQ=

main.go

@@ -3,20 +3,23 @@ package main
 import (
 	"fmt"
 
+	"git.dotya.ml/wanderer/go-xkcdreader/cmd"
+
 	"fyne.io/fyne/v2/app"
 	"fyne.io/fyne/v2/widget"
 )
 
 const appGreeting = "welcome to go-xkcdreader"
 
-// Version provides app version string
+var version = cmd.GetShortVersion()
-const Version = "0.0.0"
 
 func main() {
-	fmt.Println("Starting go-xkcdreader " + getVersion())
+	cmd.Execute()
+
+	fmt.Println("Starting " + cmd.GetAppName() + " " + getVersion())
 
 	a := app.New()
-	w := a.NewWindow("go-xkcd_reader")
+	w := a.NewWindow(cmd.GetAppName())
 
 	w.SetContent(makeGreeting())
 
@@ -30,5 +33,5 @@ func makeGreeting() *widget.Label {
 }
 
 func getVersion() string {
-	return "v" + Version
+	return version
 }

main_test.go

@@ -1,10 +1,15 @@
 package main
 
-import "testing"
+import (
+	"testing"
+
+	"git.dotya.ml/wanderer/go-xkcdreader/cmd"
+)
 
 func TestGreetingText(t *testing.T) {
-	want := "welcome to go-xkcdreader"
+	want := "welcome to " + cmd.GetAppName()
 	got := makeGreeting()
+
 	if got.Text != want {
 		t.Errorf("Incorrect initial greeting, want: %q, got: %q", want, got.Text)
 	}