remove support for terraform add command

The terraform add command was introduced in certain Terraform v1.1.0 alpha
releases in order to gather feedback. It has now been removed from Core.

Support in tfexec for terraform add was included in the same experimental vein,
with a doc comment indicating that it may be removed. Removal of Add() is
therefore not a breaking change for tfexec.

tfexec/add.go

diff --git a/tfexec/add.go b/tfexec/add.go
deleted file mode 100644
index 0e60034..0000000
--- a/tfexec/add.go
+++ /dev/null
@@ -1,101 +0,0 @@
-package tfexec
-
-import (
-	"context"
-	"fmt"
-	"os/exec"
-	"strconv"
-	"strings"
-)
-
-type addConfig struct {
-	fromState       bool
-	out             string
-	includeOptional bool
-	provider        string
-	reattachInfo    ReattachInfo
-}
-
-var defaultAddOptions = addConfig{}
-
-type AddOption interface {
-	configureAdd(*addConfig)
-}
-
-func (opt *FromStateOption) configureAdd(conf *addConfig) {
-	conf.fromState = opt.fromState
-}
-
-func (opt *OutOption) configureAdd(conf *addConfig) {
-	conf.out = opt.path
-}
-
-func (opt *IncludeOptionalOption) configureAdd(conf *addConfig) {
-	conf.includeOptional = opt.includeOptional
-}
-
-func (opt *ProviderOption) configureAdd(conf *addConfig) {
-	conf.provider = opt.provider
-}
-
-func (opt *ReattachOption) configureAdd(conf *addConfig) {
-	conf.reattachInfo = opt.info
-}
-
-// Add represents the `terraform add` subcommand (added in 1.1.0).
-//
-// Note that this function signature and behaviour is subject
-// to breaking changes including removal of that function
-// until final 1.1.0 Terraform version (with this command) is released.
-func (tf *Terraform) Add(ctx context.Context, address string, opts ...AddOption) (string, error) {
-	cmd, err := tf.addCmd(ctx, address, opts...)
-	if err != nil {
-		return "", err
-	}
-
-	var outBuf strings.Builder
-	cmd.Stdout = mergeWriters(cmd.Stdout, &outBuf)
-
-	if err := tf.runTerraformCmd(ctx, cmd); err != nil {
-		return "", err
-	}
-
-	return outBuf.String(), nil
-}
-
-func (tf *Terraform) addCmd(ctx context.Context, address string, opts ...AddOption) (*exec.Cmd, error) {
-	err := tf.compatible(ctx, tf1_1_0, nil)
-	if err != nil {
-		return nil, fmt.Errorf("terraform add was added in 1.1.0: %w", err)
-	}
-
-	c := defaultAddOptions
-
-	for _, o := range opts {
-		o.configureAdd(&c)
-	}
-
-	args := []string{"add"}
-
-	args = append(args, "-from-state="+strconv.FormatBool(c.fromState))
-	if c.out != "" {
-		args = append(args, "-out="+c.out)
-	}
-	args = append(args, "-optional="+strconv.FormatBool(c.includeOptional))
-	if c.provider != "" {
-		args = append(args, "-provider="+c.provider)
-	}
-
-	args = append(args, address)
-
-	mergeEnv := map[string]string{}
-	if c.reattachInfo != nil {
-		reattachStr, err := c.reattachInfo.marshalString()
-		if err != nil {
-			return nil, err
-		}
-		mergeEnv[reattachEnvVar] = reattachStr
-	}
-
-	return tf.buildTerraformCmd(ctx, mergeEnv, args...), nil
-}

tfexec/add_test.go

diff --git a/tfexec/add_test.go b/tfexec/add_test.go
deleted file mode 100644
index cfe92ae..0000000
--- a/tfexec/add_test.go
+++ /dev/null
@@ -1,56 +0,0 @@
-package tfexec
-
-import (
-	"context"
-	"testing"
-
-	"github.com/hashicorp/terraform-exec/tfexec/internal/testutil"
-)
-
-func TestAddCmd(t *testing.T) {
-	td := t.TempDir()
-
-	tf, err := NewTerraform(td, tfVersion(t, testutil.Latest_v1_1))
-	if err != nil {
-		t.Fatal(err)
-	}
-
-	// empty env, to avoid environ mismatch in testing
-	tf.SetEnv(map[string]string{})
-
-	t.Run("default", func(t *testing.T) {
-		addCmd, err := tf.addCmd(context.Background(), "my-addr")
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		assertCmd(t, []string{
-			"add",
-			"-from-state=false",
-			"-optional=false",
-			"my-addr",
-		}, nil, addCmd)
-	})
-
-	t.Run("override-default", func(t *testing.T) {
-		addCmd, err := tf.addCmd(context.Background(),
-			"my-addr",
-			FromState(true),
-			Out("out"),
-			IncludeOptional(true),
-			Provider("my-provider"),
-		)
-		if err != nil {
-			t.Fatal(err)
-		}
-
-		assertCmd(t, []string{
-			"add",
-			"-from-state=true",
-			"-out=out",
-			"-optional=true",
-			"-provider=my-provider",
-			"my-addr",
-		}, nil, addCmd)
-	})
-}

tfexec/options.go

diff --git a/tfexec/options.go b/tfexec/options.go
index fb2d5bd..7163889 100644
--- a/tfexec/options.go
+++ b/tfexec/options.go
@@ -373,21 +373,3 @@
 func VerifyPlugins(verifyPlugins bool) *VerifyPluginsOption {
 	return &VerifyPluginsOption{verifyPlugins}
 }
-
-// FromStateOption represents the -from-state option of the "terraform add" command.
-type FromStateOption struct {
-	fromState bool
-}
-
-func FromState(fromState bool) *FromStateOption {
-	return &FromStateOption{fromState}
-}
-
-// IncludeOptionalOption represents the -optional option of the "terraform add" command.
-type IncludeOptionalOption struct {
-	includeOptional bool
-}
-
-func IncludeOptional(includeOptional bool) *IncludeOptionalOption {
-	return &IncludeOptionalOption{includeOptional}
-}