chore: move the experiments package out of the internal/ dir

Closes #2014

experiments/errors.go

@@ -0,0 +1,35 @@
+package experiments
+
+import (
+	"fmt"
+	"strconv"
+	"strings"
+
+	"github.com/go-task/task/v3/internal/slicesext"
+)
+
+type InvalidValueError struct {
+	Name          string
+	AllowedValues []int
+	Value         int
+}
+
+func (err InvalidValueError) Error() string {
+	return fmt.Sprintf(
+		"task: Experiment %q has an invalid value %q (allowed values: %s)",
+		err.Name,
+		err.Value,
+		strings.Join(slicesext.Convert(err.AllowedValues, strconv.Itoa), ", "),
+	)
+}
+
+type InactiveError struct {
+	Name string
+}
+
+func (err InactiveError) Error() string {
+	return fmt.Sprintf(
+		"task: Experiment %q is inactive and cannot be enabled",
+		err.Name,
+	)
+}

experiments/experiment.go

@@ -0,0 +1,67 @@
+package experiments
+
+import (
+	"fmt"
+	"slices"
+	"strconv"
+
+	"github.com/go-task/task/v3/taskrc/ast"
+)
+
+type Experiment struct {
+	Name          string // The name of the experiment.
+	AllowedValues []int  // The values that can enable this experiment.
+	Value         int    // The version of the experiment that is enabled.
+}
+
+// New creates a new experiment with the given name and sets the values that can
+// enable it.
+func New(xName string, config *ast.TaskRC, allowedValues ...int) Experiment {
+	var value int
+	if config != nil {
+		value = config.Experiments[xName]
+	}
+
+	if value == 0 {
+		value, _ = strconv.Atoi(getEnv(xName))
+	}
+
+	x := Experiment{
+		Name:          xName,
+		AllowedValues: allowedValues,
+		Value:         value,
+	}
+	xList = append(xList, x)
+	return x
+}
+
+func (x Experiment) Enabled() bool {
+	return slices.Contains(x.AllowedValues, x.Value)
+}
+
+func (x Experiment) Active() bool {
+	return len(x.AllowedValues) > 0
+}
+
+func (x Experiment) Valid() error {
+	if !x.Active() && x.Value != 0 {
+		return &InactiveError{
+			Name: x.Name,
+		}
+	}
+	if !x.Enabled() && x.Value != 0 {
+		return &InvalidValueError{
+			Name:          x.Name,
+			AllowedValues: x.AllowedValues,
+			Value:         x.Value,
+		}
+	}
+	return nil
+}
+
+func (x Experiment) String() string {
+	if x.Enabled() {
+		return fmt.Sprintf("on (%d)", x.Value)
+	}
+	return "off"
+}

experiments/experiment_test.go

@@ -0,0 +1,140 @@
+package experiments_test
+
+import (
+	"strconv"
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+
+	"github.com/go-task/task/v3/experiments"
+	"github.com/go-task/task/v3/taskrc/ast"
+)
+
+func TestNew(t *testing.T) {
+	const (
+		exampleExperiment    = "EXAMPLE"
+		exampleExperimentEnv = "TASK_X_EXAMPLE"
+	)
+	tests := []struct {
+		name          string
+		config        *ast.TaskRC
+		allowedValues []int
+		env           int
+		wantEnabled   bool
+		wantActive    bool
+		wantValid     error
+		wantValue     int
+	}{
+		{
+			name:        `[] allowed, env=""`,
+			wantEnabled: false,
+			wantActive:  false,
+		},
+		{
+			name:        `[] allowed, env="1"`,
+			env:         1,
+			wantEnabled: false,
+			wantActive:  false,
+			wantValid: &experiments.InactiveError{
+				Name: exampleExperiment,
+			},
+			wantValue: 1,
+		},
+		{
+			name:          `[1] allowed, env=""`,
+			allowedValues: []int{1},
+			wantEnabled:   false,
+			wantActive:    true,
+		},
+		{
+			name:          `[1] allowed, env="1"`,
+			allowedValues: []int{1},
+			env:           1,
+			wantEnabled:   true,
+			wantActive:    true,
+			wantValue:     1,
+		},
+		{
+			name:          `[1] allowed, env="2"`,
+			allowedValues: []int{1},
+			env:           2,
+			wantEnabled:   false,
+			wantActive:    true,
+			wantValid: &experiments.InvalidValueError{
+				Name:          exampleExperiment,
+				AllowedValues: []int{1},
+				Value:         2,
+			},
+			wantValue: 2,
+		},
+		{
+			name:          `[1, 2] allowed, env="1"`,
+			allowedValues: []int{1, 2},
+			env:           1,
+			wantEnabled:   true,
+			wantActive:    true,
+			wantValue:     1,
+		},
+		{
+			name:          `[1, 2] allowed, env="1"`,
+			allowedValues: []int{1, 2},
+			env:           2,
+			wantEnabled:   true,
+			wantActive:    true,
+			wantValue:     2,
+		},
+		{
+			name: `[1] allowed, config="1"`,
+			config: &ast.TaskRC{
+				Experiments: map[string]int{
+					exampleExperiment: 1,
+				},
+			},
+			allowedValues: []int{1},
+			wantEnabled:   true,
+			wantActive:    true,
+			wantValue:     1,
+		},
+		{
+			name: `[1] allowed, config="2"`,
+			config: &ast.TaskRC{
+				Experiments: map[string]int{
+					exampleExperiment: 2,
+				},
+			},
+			allowedValues: []int{1},
+			wantEnabled:   false,
+			wantActive:    true,
+			wantValid: &experiments.InvalidValueError{
+				Name:          exampleExperiment,
+				AllowedValues: []int{1},
+				Value:         2,
+			},
+			wantValue: 2,
+		},
+		{
+			name: `[1, 2] allowed, env="1", config="2"`,
+			config: &ast.TaskRC{
+				Experiments: map[string]int{
+					exampleExperiment: 2,
+				},
+			},
+			allowedValues: []int{1, 2},
+			env:           1,
+			wantEnabled:   true,
+			wantActive:    true,
+			wantValue:     2,
+		},
+	}
+	for _, tt := range tests {
+		t.Run(tt.name, func(t *testing.T) {
+			t.Setenv(exampleExperimentEnv, strconv.Itoa(tt.env))
+			x := experiments.New(exampleExperiment, tt.config, tt.allowedValues...)
+			assert.Equal(t, exampleExperiment, x.Name)
+			assert.Equal(t, tt.wantEnabled, x.Enabled())
+			assert.Equal(t, tt.wantActive, x.Active())
+			assert.Equal(t, tt.wantValid, x.Valid())
+			assert.Equal(t, tt.wantValue, x.Value)
+		})
+	}
+}

experiments/experiments.go

@@ -0,0 +1,91 @@
+package experiments
+
+import (
+	"fmt"
+	"os"
+	"path/filepath"
+	"strings"
+
+	"github.com/joho/godotenv"
+
+	"github.com/go-task/task/v3/taskrc"
+)
+
+const envPrefix = "TASK_X_"
+
+// Active experiments.
+var (
+	GentleForce     Experiment
+	RemoteTaskfiles Experiment
+	EnvPrecedence   Experiment
+)
+
+// Inactive experiments. These are experiments that cannot be enabled, but are
+// preserved for error handling.
+var (
+	AnyVariables Experiment
+	MapVariables Experiment
+)
+
+// An internal list of all the initialized experiments used for iterating.
+var xList []Experiment
+
+func Parse(dir string) {
+	// Read any .env files
+	readDotEnv(dir)
+
+	// Create a node for the Task config reader
+	node, _ := taskrc.NewNode("", dir)
+
+	// Read the Task config file
+	reader := taskrc.NewReader()
+	config, _ := reader.Read(node)
+
+	// Initialize the experiments
+	GentleForce = New("GENTLE_FORCE", config, 1)
+	RemoteTaskfiles = New("REMOTE_TASKFILES", config, 1)
+	EnvPrecedence = New("ENV_PRECEDENCE", config, 1)
+	AnyVariables = New("ANY_VARIABLES", config)
+	MapVariables = New("MAP_VARIABLES", config)
+}
+
+// Validate checks if any experiments have been enabled while being inactive.
+// If one is found, the function returns an error.
+func Validate() error {
+	for _, x := range List() {
+		if err := x.Valid(); err != nil {
+			return err
+		}
+	}
+	return nil
+}
+
+func List() []Experiment {
+	return xList
+}
+
+func getEnv(xName string) string {
+	envName := fmt.Sprintf("%s%s", envPrefix, xName)
+	return os.Getenv(envName)
+}
+
+func getFilePath(filename, dir string) string {
+	if dir != "" {
+		return filepath.Join(dir, filename)
+	}
+	return filename
+}
+
+func readDotEnv(dir string) {
+	env, err := godotenv.Read(getFilePath(".env", dir))
+	if err != nil {
+		return
+	}
+
+	// If the env var is an experiment, set it.
+	for key, value := range env {
+		if strings.HasPrefix(key, envPrefix) {
+			os.Setenv(key, value)
+		}
+	}
+}