Add Preconditions to Tasks

internal/taskfile/precondition.go

@@ -0,0 +1,51 @@
+package taskfile
+
+import (
+	"errors"
+	"fmt"
+)
+
+var (
+	// ErrCantUnmarshalPrecondition is returned for invalid precond YAML.
+	ErrCantUnmarshalPrecondition = errors.New("task: can't unmarshal precondition value")
+)
+
+// Precondition represents a precondition necessary for a task to run
+type Precondition struct {
+	Sh          string
+	Msg         string
+	IgnoreError bool
+}
+
+// UnmarshalYAML implements yaml.Unmarshaler interface.
+func (p *Precondition) UnmarshalYAML(unmarshal func(interface{}) error) error {
+	var cmd string
+
+	if err := unmarshal(&cmd); err == nil {
+		p.Sh = cmd
+		p.Msg = fmt.Sprintf("`%s` failed", cmd)
+		p.IgnoreError = false
+		return nil
+	}
+
+	var sh struct {
+		Sh          string
+		Msg         string
+		IgnoreError bool `yaml:"ignore_error"`
+	}
+
+	err := unmarshal(&sh)
+
+	if err == nil {
+		p.Sh = sh.Sh
+		p.Msg = sh.Msg
+		if p.Msg == "" {
+			p.Msg = fmt.Sprintf("%s failed", sh.Sh)
+		}
+
+		p.IgnoreError = sh.IgnoreError
+		return nil
+	}
+
+	return err
+}

internal/taskfile/precondition_test.go

@@ -0,0 +1,49 @@
+package taskfile_test
+
+import (
+	"testing"
+
+	"github.com/go-task/task/v2/internal/taskfile"
+
+	"github.com/stretchr/testify/assert"
+	"gopkg.in/yaml.v2"
+)
+
+func TestPreconditionParse(t *testing.T) {
+	tests := []struct {
+		content  string
+		v        interface{}
+		expected interface{}
+	}{
+		{
+			"test -f foo.txt",
+			&taskfile.Precondition{},
+			&taskfile.Precondition{Sh: `test -f foo.txt`, Msg: "`test -f foo.txt` failed", IgnoreError: false},
+		},
+		{
+			"sh: '[ 1 = 0 ]'",
+			&taskfile.Precondition{},
+			&taskfile.Precondition{Sh: "[ 1 = 0 ]", Msg: "[ 1 = 0 ] failed", IgnoreError: false},
+		},
+		{`
+sh: "[ 1 = 2 ]"
+msg: "1 is not 2"
+`,
+			&taskfile.Precondition{},
+			&taskfile.Precondition{Sh: "[ 1 = 2 ]", Msg: "1 is not 2", IgnoreError: false},
+		},
+		{`
+sh: "[ 1 = 2 ]"
+msg: "1 is not 2"
+ignore_error: true
+`,
+			&taskfile.Precondition{},
+			&taskfile.Precondition{Sh: "[ 1 = 2 ]", Msg: "1 is not 2", IgnoreError: true},
+		},
+	}
+	for _, test := range tests {
+		err := yaml.Unmarshal([]byte(test.content), test.v)
+		assert.NoError(t, err)
+		assert.Equal(t, test.expected, test.v)
+	}
+}

internal/taskfile/task.go

@@ -5,19 +5,20 @@ type Tasks map[string]*Task
 
 // Task represents a task
 type Task struct {
-	Task        string
-	Cmds        []*Cmd
-	Deps        []*Dep
-	Desc        string
-	Summary     string
-	Sources     []string
-	Generates   []string
-	Status      []string
-	Dir         string
-	Vars        Vars
-	Env         Vars
-	Silent      bool
-	Method      string
-	Prefix      string
-	IgnoreError bool `yaml:"ignore_error"`
+	Task         string
+	Cmds         []*Cmd
+	Deps         []*Dep
+	Desc         string
+	Summary      string
+	Sources      []string
+	Generates    []string
+	Status       []string
+	Precondition []*Precondition
+	Dir          string
+	Vars         Vars
+	Env          Vars
+	Silent       bool
+	Method       string
+	Prefix       string
+	IgnoreError  bool `yaml:"ignore_error"`
 }

internal/taskfile/version/version.go

@@ -10,6 +10,8 @@ var (
 	v21 = mustVersion("2.1")
 	v22 = mustVersion("2.2")
 	v23 = mustVersion("2.3")
+	v24 = mustVersion("2.4")
+	v25 = mustVersion("2.5")
 )
 
 // IsV1 returns if is a given Taskfile version is version 1
@@ -37,6 +39,16 @@ func IsV23(v *semver.Constraints) bool {
 	return v.Check(v23)
 }
 
+// IsV24 returns if is a given Taskfile version is at least version 2.4
+func IsV24(v *semver.Constraints) bool {
+	return v.Check(v24)
+}
+
+// IsV25 returns if is a given Taskfile version is at least version 2.5
+func IsV25(v *semver.Constraints) bool {
+	return v.Check(v25)
+}
+
 func mustVersion(s string) *semver.Version {
 	v, err := semver.NewVersion(s)
 	if err != nil {