Use semver for Taskfile versions

Gopkg.toml

@@ -38,3 +38,7 @@
 [[constraint]]
   branch = "master"
   name = "github.com/mitchellh/go-homedir"
+
+[[constraint]]
+  branch = "master"
+  name = "github.com/Masterminds/semver"

internal/taskfile/taskfile.go

@@ -2,8 +2,7 @@ package taskfile
 
 // Taskfile represents a Taskfile.yml
 type Taskfile struct {
-	// TODO: version is still not used
-	Version int
+	Version string
 	Tasks   Tasks
 }
 
@@ -14,7 +13,7 @@ func (tf *Taskfile) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	}
 
 	var taskfile struct {
-		Version int
+		Version string
 		Tasks   Tasks
 	}
 	if err := unmarshal(&taskfile); err != nil {

internal/taskfile/version/version.go

@@ -0,0 +1,45 @@
+package version
+
+import (
+	"github.com/Masterminds/semver"
+)
+
+var (
+	v1 = mustVersion("1")
+	v2 = mustVersion("2")
+
+	isV1  = mustConstraint("= 1")
+	isV2  = mustConstraint(">= 2")
+	isV21 = mustConstraint(">= 2.1")
+)
+
+// IsV1 returns if is a given Taskfile version is version 1
+func IsV1(v *semver.Version) bool {
+	return isV1.Check(v)
+}
+
+// IsV2 returns if is a given Taskfile version is at least version 2
+func IsV2(v *semver.Version) bool {
+	return isV2.Check(v)
+}
+
+// IsV21 returns if is a given Taskfile version is at least version 2
+func IsV21(v *semver.Version) bool {
+	return isV21.Check(v)
+}
+
+func mustVersion(s string) *semver.Version {
+	v, err := semver.NewVersion(s)
+	if err != nil {
+		panic(err)
+	}
+	return v
+}
+
+func mustConstraint(s string) *semver.Constraints {
+	c, err := semver.NewConstraint(s)
+	if err != nil {
+		panic(err)
+	}
+	return c
+}

task.go

@@ -13,7 +13,9 @@ import (
 	"github.com/go-task/task/internal/execext"
 	"github.com/go-task/task/internal/logger"
 	"github.com/go-task/task/internal/taskfile"
+	"github.com/go-task/task/internal/taskfile/version"
 
+	"github.com/Masterminds/semver"
 	"golang.org/x/sync/errgroup"
 )
 
@@ -76,9 +78,14 @@ func (e *Executor) Run(calls ...taskfile.Call) error {
 }
 
 func (e *Executor) setup() error {
-	if e.Taskfile.Version == 0 {
-		e.Taskfile.Version = 1
+	if e.Taskfile.Version == "" {
+		e.Taskfile.Version = "1"
 	}
+	v, err := semver.NewVersion(e.Taskfile.Version)
+	if err != nil {
+		return fmt.Errorf(`task: could not parse taskfile version "%s": %v`, e.Taskfile.Version, err)
+	}
+
 	if e.Context == nil {
 		e.Context = context.Background()
 	}
@@ -96,14 +103,14 @@ func (e *Executor) setup() error {
 		Stderr:  e.Stderr,
 		Verbose: e.Verbose,
 	}
-	switch e.Taskfile.Version {
-	case 1:
+	switch {
+	case version.IsV1(v):
 		e.Compiler = &compilerv1.CompilerV1{
 			Dir:    e.Dir,
 			Vars:   e.taskvars,
 			Logger: e.Logger,
 		}
-	case 2:
+	case version.IsV2(v):
 		e.Compiler = &compilerv2.CompilerV2{
 			Dir:    e.Dir,
 			Vars:   e.taskvars,
@@ -113,8 +120,8 @@ func (e *Executor) setup() error {
 		if !e.Silent {
 			e.Logger.Errf(`task: warning: Taskfile "version: 2" is experimental and implementation can change before v2.0.0 release`)
 		}
-	default:
-		return fmt.Errorf(`task: Unrecognized Taskfile version "%d"`, e.Taskfile.Version)
+	case version.IsV21(v):
+		return fmt.Errorf(`task: Taskfile versions greater than v2 not implemented in the version of Task`)
 	}
 
 	e.taskCallCount = make(map[string]*int32, len(e.Taskfile.Tasks))

task_test.go

@@ -392,10 +392,10 @@ func TestCyclicDep(t *testing.T) {
 func TestTaskVersion(t *testing.T) {
 	tests := []struct {
 		Dir     string
-		Version int
+		Version string
 	}{
-		{"testdata/version/v1", 1},
-		{"testdata/version/v2", 2},
+		{"testdata/version/v1", "1"},
+		{"testdata/version/v2", "2"},
 	}
 
 	for _, test := range tests {

testdata/vars/v2/Taskfile.yml

@@ -1,4 +1,4 @@
-version: 2
+version: '2'
 tasks:
   default:
     deps: [hello]

testdata/vars/v2/multiline/Taskfile.yml

@@ -1,4 +1,4 @@
-version: 2
+version: '2'
 tasks:
   default:
     vars: