Update set outputs to latest specs

See https://github.blog/changelog/2022-10-11-github-actions-deprecating-save-state-and-set-output-commands/
and https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#environment-files

.github/workflows/ci.yml

@@ -22,7 +22,7 @@ jobs:
       id: gofmt
       run: |
         gofmt -w .
-        echo ::set-output name=formatted_files::$(git status -s -uno | wc -l)
+        echo "formatted_files=$(git status -s -uno | wc -l)" >> $GITHUB_OUTPUT
 
     - name: push formatting fixes
       if: steps.gofmt.outputs.formatted_files > 0
@@ -62,8 +62,18 @@ jobs:
       run: go mod download
 
     - name: run tests
+      id: tests
       if: ${{ matrix.os }} != "windows-latest"
       env:
         # unauthenticated calls have lower limits than authenticated ones
         GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
       run: go test -v -race ${{ matrix.coverageArgs }} ./...
+
+    - name: run tests with inputs
+      if: ${{ matrix.os }} != "windows-latest"
+      env:
+        ACTIONS_OUTPUT_SET: "true"
+        # unauthenticated calls have lower limits than authenticated ones
+        GITHUB_TOKEN: ${{ secrets.GITHUB_TOKEN }}
+        my_output: "${{ steps.tests.outputs.my-output }}"
+      run: go test -v -run TestOutputTasks ./...

core/command.go

@@ -48,7 +48,7 @@ func IssueCommand(kind string, properties map[string]string, message string) {
 // issueFileCommand implements stores the command in a file
 // see https://github.com/actions/toolkit/pull/571/files#diff-9ce6eb99f5fb5529e795254801e03ae56d67d3d5fcbec635f91e9a8a61ad8b64R10
 func issueFileCommand(command string, message string) error {
-	path, ok := os.LookupEnv("GITHUB_" + command)
+	path, ok := os.LookupEnv(command)
 	if ok {
 		fd, err := os.OpenFile(path, os.O_RDWR, 0)
 		if err != nil {
@@ -57,7 +57,7 @@ func issueFileCommand(command string, message string) error {
 		fmt.Fprintln(fd, message)
 		return nil
 	}
-	return fmt.Errorf("unable to find command file GITHUB_%s", command)
+	return fmt.Errorf("unable to find command file %s", command)
 }
 
 type command struct {

core/core.go

@@ -2,28 +2,60 @@ package core
 
 import (
 	"fmt"
+	"io"
 	"os"
 	"strings"
 	"sync"
 )
 
 const (
+	delimiter = "_GitHubActionsGoFileCommandDelimeter_"
+
 	// StatusFailed is returned by Status() in case this action has been marked as failed
 	StatusFailed = 1
 	// StatusSuccess is returned by Status() in case this action has not been marked as failed. By default an action is claimed as successful
 	StatusSuccess = 0
+
+	GitHubOutputFilePathEnvName    = "GITHUB_OUTPUT"
+	GitHubStateFilePathEnvName     = "GITHUB_STATE"
+	GitHubExportEnvFilePathEnvName = "GITHUB_ENV"
+	GitHubPathFilePathEnvName      = "GITHUB_PATH"
 )
 
 var (
 	status       = StatusSuccess
 	statusAccess = &sync.Mutex{}
 	lookupEnv    = os.LookupEnv
+	open         = func(path string, flag int, perm os.FileMode) (File, error) {
+		fd, err := os.OpenFile(path, flag, perm)
+		if err != nil {
+			return nil, err
+		}
+		return fd, nil
+	}
 )
 
+type File interface {
+	io.Reader
+	io.Writer
+	io.Closer
+}
+
+func formatOutput(name, value string) string {
+	return strings.Join(
+		[]string{
+			fmt.Sprintf("%s<<%s", name, delimiter),
+			value,
+			delimiter,
+			"",
+		},
+		EOF,
+	)
+}
+
 // ExportVariable sets the environment varaible name (for this action and future actions)
 func ExportVariable(name, value string) {
-	const delimiter = "_GitHubActionsFileCommandDelimeter_"
-	if err := issueFileCommand("ENV", fmt.Sprintf("%s<<%s%s%s%s%s", name, delimiter, EOF, value, delimiter, EOF)); err != nil {
+	if err := issueFileCommand(GitHubExportEnvFilePathEnvName, formatOutput(name, value)); err != nil {
 		IssueCommand("set-env", map[string]string{"name": name}, value)
 	}
 	os.Setenv(name, value)
@@ -36,7 +68,7 @@ func SetSecret(secret string) {
 
 // AddPath prepends inputPath to the PATH (for this action and future actions)
 func AddPath(path string) {
-	if err := issueFileCommand("PATH", path); err != nil {
+	if err := issueFileCommand(GitHubPathFilePathEnvName, path); err != nil {
 		Issue("add-path", path)
 	}
 	// TODO js: process.env['PATH'] = `${inputPath}${path.delimiter}${process.env['PATH']}`
@@ -65,7 +97,10 @@ func GetInputOrDefault(name, dflt string) string {
 
 // SetOutput sets the value of an output for future actions
 func SetOutput(name, value string) {
-	IssueCommand("set-output", map[string]string{"name": name}, value)
+	if err := issueFileCommand(GitHubOutputFilePathEnvName, formatOutput(name, value)); err != nil {
+		Warningf("did not find output file from environment variable %s, falling back to the deprecated command implementation", GitHubOutputFilePathEnvName)
+		IssueCommand("set-output", map[string]string{"name": name}, value)
+	}
 }
 
 // SetFailedf sets the action status to failed and sets an error message
@@ -142,7 +177,10 @@ func Group(name string, f func()) func() {
 
 // SaveState saves state for current action, the state can only be retrieved by this action's post job execution.
 func SaveState(name, value string) {
-	IssueCommand("save-state", map[string]string{"name": name}, value)
+	if err := issueFileCommand(GitHubStateFilePathEnvName, formatOutput(name, value)); err != nil {
+		Warningf("did not find state file from environment variable %s, falling back to the deprecated command implementation", GitHubStateFilePathEnvName)
+		IssueCommand("save-state", map[string]string{"name": name}, value)
+	}
 }
 
 // GetState gets the value of an state set by this action's main execution.

core/core_test.go

@@ -1,11 +1,33 @@
 package core
 
 import (
+	"os"
+	"runtime"
 	"testing"
 
 	"github.com/stretchr/testify/assert"
 )
 
+func TestFormatOutput(t *testing.T) {
+	if runtime.GOOS == "windows" {
+		t.Skip("This test only runs on unix with \\n line separator")
+	}
+	assert.Equal(t, "my-name<<_GitHubActionsGoFileCommandDelimeter_\nmy-value\n_GitHubActionsGoFileCommandDelimeter_\n", formatOutput("my-name", "my-value"))
+}
+
+func TestOutputTasks(t *testing.T) {
+	if _, ok := os.LookupEnv("ACTIONS_OUTPUT_SET"); ok {
+		// state is only available in pre and post actions:
+		// https://docs.github.com/en/actions/using-workflows/workflow-commands-for-github-actions#sending-values-to-the-pre-and-post-actions
+		// assert.Equal(t, "my-state-value", GetState("my-state"))
+		assert.Equal(t, "my-output-value", os.Getenv("my_output"))
+		assert.Equal(t, "my-env-value", os.Getenv("my_env"))
+	}
+	SaveState("my-state", "my-state-value")
+	ExportVariable("my_env", "my-env-value")
+	SetOutput("my-output", "my-output-value")
+}
+
 func TestGetInput(t *testing.T) {
 	t.Run("when environment variable is not net", func(t *testing.T) {
 		lookupEnv = func(name string) (string, bool) {

github/context.go

@@ -6,6 +6,7 @@ import (
 	"os"
 	"strings"
 
+	"github.com/actions-go/toolkit/core"
 	"github.com/google/go-github/v42/github"
 )
 
@@ -79,15 +80,18 @@ type ActionRepo struct {
 
 // ActionContext contains details on the workflow execution
 type ActionContext struct {
-	Payload   WebhookPayload
-	EventName string
-	SHA       string
-	Ref       string
-	Workflow  string
-	Action    string
-	Actor     string
-	Issue     ActionIssue
-	Repo      ActionRepo
+	Payload           WebhookPayload
+	EventName         string
+	SHA               string
+	Ref               string
+	Workflow          string
+	Action            string
+	Actor             string
+	Issue             ActionIssue
+	Repo              ActionRepo
+	OutputFilePath    string
+	StateFilePath     string
+	ExportEnvFilePath string
 }
 
 func noGitHubEvent(path string) {
@@ -109,13 +113,16 @@ func ParseActionEnv() ActionContext {
 		Repo:  getIndex(r, 1),
 	}
 	ctx := ActionContext{
-		EventName: os.Getenv("GITHUB_EVENT_NAME"),
-		SHA:       os.Getenv("GITHUB_SHA"),
-		Ref:       os.Getenv("GITHUB_REF"),
-		Workflow:  os.Getenv("GITHUB_WORKFLOW"),
-		Action:    os.Getenv("GITHUB_ACTION"),
-		Actor:     os.Getenv("GITHUB_ACTOR"),
-		Repo:      repo,
+		EventName:         os.Getenv("GITHUB_EVENT_NAME"),
+		SHA:               os.Getenv("GITHUB_SHA"),
+		Ref:               os.Getenv("GITHUB_REF"),
+		Workflow:          os.Getenv("GITHUB_WORKFLOW"),
+		Action:            os.Getenv("GITHUB_ACTION"),
+		Actor:             os.Getenv("GITHUB_ACTOR"),
+		OutputFilePath:    os.Getenv(core.GitHubOutputFilePathEnvName),
+		StateFilePath:     os.Getenv(core.GitHubStateFilePathEnvName),
+		ExportEnvFilePath: os.Getenv(core.GitHubExportEnvFilePathEnvName),
+		Repo:              repo,
 		Issue: ActionIssue{
 			Owner: repo.Owner,
 			Repo:  repo.Repo,