chore(tests): use detected Terraform if available.

Add support for running e2e tests with a different version of
Terraform when exporting the `TM_TEST_TERRAFORM_REQUIRED_VERSION`
environment variable.

Additionally, the tests now detect if Terraform is already
installed and then the detected version is used. If the detected
version does not match the version provided in the environment
variable, then it's installed as before.

Signed-off-by: Tiago Natel <t.nateldemoura@gmail.com>

cmd/terramate/e2etests/_testdata/cloud-sync-drift-plan-file/sanitized.plan.json

@@ -1 +1 @@
-{"format_version":"1.2","terraform_version":"1.5.0","variables":{"content":{"value":"REDACTED_SENSITIVE"}},"planned_values":{"root_module":{"resources":[{"address":"local_file.foo","mode":"managed","type":"local_file","name":"foo","provider_name":"registry.terraform.io/hashicorp/local","schema_version":0,"values":{"content":"REDACTED_SENSITIVE","content_base64":null,"directory_permission":"0777","file_permission":"0777","filename":"./foo.bar","sensitive_content":"REDACTED_SENSITIVE","source":null},"sensitive_values":{"content":true}}]}},"resource_changes":[{"address":"local_file.foo","mode":"managed","type":"local_file","name":"foo","provider_name":"registry.terraform.io/hashicorp/local","change":{"actions":["create"],"before":null,"after":{"content":"REDACTED_SENSITIVE","content_base64":null,"directory_permission":"0777","file_permission":"0777","filename":"./foo.bar","sensitive_content":"REDACTED_SENSITIVE","source":null},"after_unknown":{"content_base64sha256":true,"content_base64sha512":true,"content_md5":true,"content_sha1":true,"content_sha256":true,"content_sha512":true,"id":true},"before_sensitive":false,"after_sensitive":{"content":true,"sensitive_content":true}}}],"configuration":{"provider_config":{"local":{"name":"local","full_name":"registry.terraform.io/hashicorp/local"}},"root_module":{"resources":[{"address":"local_file.foo","mode":"managed","type":"local_file","name":"foo","provider_config_key":"local","expressions":{"content":{"references":["var.content"]},"filename":{"references":["path.module"]}},"schema_version":0}],"variables":{"content":{"sensitive":true}}}},"timestamp":"2023-10-12T14:03:39Z"}
+{"format_version":"1.2","terraform_version":"__terraform_version__","variables":{"content":{"value":"REDACTED_SENSITIVE"}},"planned_values":{"root_module":{"resources":[{"address":"local_file.foo","mode":"managed","type":"local_file","name":"foo","provider_name":"registry.terraform.io/hashicorp/local","schema_version":0,"values":{"content":"REDACTED_SENSITIVE","content_base64":null,"directory_permission":"0777","file_permission":"0777","filename":"./foo.bar","sensitive_content":"REDACTED_SENSITIVE","source":null},"sensitive_values":{"content":true}}]}},"resource_changes":[{"address":"local_file.foo","mode":"managed","type":"local_file","name":"foo","provider_name":"registry.terraform.io/hashicorp/local","change":{"actions":["create"],"before":null,"after":{"content":"REDACTED_SENSITIVE","content_base64":null,"directory_permission":"0777","file_permission":"0777","filename":"./foo.bar","sensitive_content":"REDACTED_SENSITIVE","source":null},"after_unknown":{"content_base64sha256":true,"content_base64sha512":true,"content_md5":true,"content_sha1":true,"content_sha256":true,"content_sha512":true,"id":true},"before_sensitive":false,"after_sensitive":{"content":true,"sensitive_content":true}}}],"configuration":{"provider_config":{"local":{"name":"local","full_name":"registry.terraform.io/hashicorp/local"}},"root_module":{"resources":[{"address":"local_file.foo","mode":"managed","type":"local_file","name":"foo","provider_config_key":"local","expressions":{"content":{"references":["var.content"]},"filename":{"references":["path.module"]}},"schema_version":0}],"variables":{"content":{"sensitive":true}}}},"timestamp":"2023-10-12T14:03:39Z"}

cmd/terramate/e2etests/main_test.go

@@ -11,6 +11,7 @@ import (
 	"os/exec"
 	"path/filepath"
 	"runtime"
+	"strings"
 	"testing"
 	"time"
 
@@ -22,14 +23,17 @@ import (
 	"github.com/terramate-io/terramate/errors"
 )
 
-const terraformVersion = "1.5.0"
+const terraformInstallVersion = "1.5.0"
 
 // terramateTestBin is the path to the terramate binary we compiled for test purposes
 var terramateTestBin string
 
 // terraformTestBin is the path to the installed terraform binary.
 var terraformTestBin string
 
+// terraformVersion is the detected or installed Terraform version.
+var terraformVersion string
+
 // testHelperBin is the path to the test binary we compiled for test purposes
 var testHelperBin string
 
@@ -89,21 +93,14 @@ func setupAndRunTests(m *testing.M) (status int) {
 	EOF
 	)}`, testHelperBin)
 
-	tfExecPath, installer, err := installTerraform()
+	tfExecPath, cleanup, err := installTerraform()
 	if err != nil {
 		log.Printf("failed to setup Terraform binary")
 		return 1
 	}
-
+	defer cleanup()
 	terraformTestBin = tfExecPath
 
-	defer func() {
-		err := installer.Remove(context.Background())
-		if err != nil {
-			log.Printf("failed to remove terraform installation")
-		}
-	}()
-
 	return m.Run()
 }
 
@@ -146,12 +143,33 @@ func buildTerramate(goBin, projectRoot, binDir string) (string, error) {
 	return outBinPath, nil
 }
 
-func installTerraform() (string, *install.Installer, error) {
+func installTerraform() (string, func(), error) {
+	requireVersion := os.Getenv("TM_TEST_TERRAFORM_REQUIRED_VERSION")
+	tfExecPath, err := exec.LookPath("terraform")
+	if err == nil {
+		cmd := exec.Command("terraform", "version")
+		output, err := cmd.Output()
+		if err == nil && len(output) > 0 {
+			lines := strings.Split(string(output), "\n")
+			terraformVersion = strings.TrimPrefix(strings.TrimSpace(lines[0]), "Terraform v")
+
+			if requireVersion == "" || terraformVersion == requireVersion {
+				log.Printf("Terraform detected version: %s", terraformVersion)
+				return tfExecPath, func() {}, nil
+			}
+		}
+	}
+
+	installVersion := terraformInstallVersion
+	if requireVersion != "" {
+		installVersion = requireVersion
+	}
+
 	ctx, cancel := context.WithTimeout(context.Background(), 1*time.Minute)
 	defer cancel()
 
 	installer := install.NewInstaller()
-	version := version.Must(version.NewVersion(terraformVersion))
+	version := version.Must(version.NewVersion(installVersion))
 
 	execPath, err := installer.Install(ctx, []src.Installable{
 		&releases.ExactVersion{
@@ -162,7 +180,14 @@ func installTerraform() (string, *install.Installer, error) {
 	if err != nil {
 		return "", nil, errors.E(err, "installing Terraform")
 	}
-	return execPath, installer, nil
+	terraformVersion = installVersion
+	log.Printf("Terraform installed version: %s", terraformVersion)
+	return execPath, func() {
+		err := installer.Remove(context.Background())
+		if err != nil {
+			log.Printf("failed to remove terraform installation")
+		}
+	}, nil
 }
 
 func lookupGoBin() (string, error) {

cmd/terramate/e2etests/run_cloud_drift_test.go

@@ -380,7 +380,7 @@ func TestCLIRunWithCloudSyncDriftStatus(t *testing.T) {
 							Status: stack.Drifted,
 							Details: &cloud.DriftDetails{
 								Provisioner:   "terraform",
-								ChangesetJSON: string(test.ReadFile(t, "_testdata/cloud-sync-drift-plan-file", "sanitized.plan.json")),
+								ChangesetJSON: loadJSONPlan(t, "_testdata/cloud-sync-drift-plan-file/sanitized.plan.json"),
 							},
 						},
 						ChangesetASCIIRegexes: []string{
@@ -399,7 +399,7 @@ func TestCLIRunWithCloudSyncDriftStatus(t *testing.T) {
 							Status: stack.Drifted,
 							Details: &cloud.DriftDetails{
 								Provisioner:   "terraform",
-								ChangesetJSON: string(test.ReadFile(t, "_testdata/cloud-sync-drift-plan-file", "sanitized.plan.json")),
+								ChangesetJSON: loadJSONPlan(t, "_testdata/cloud-sync-drift-plan-file/sanitized.plan.json"),
 							},
 						},
 						ChangesetASCIIRegexes: []string{
@@ -512,10 +512,21 @@ func assertRunDrifts(t *testing.T, expectedDrifts expectedDriftStackPayloadReque
 		assert.NoError(t, json.Unmarshal([]byte(got.Details.ChangesetJSON), &gotPlan))
 		assert.NoError(t, json.Unmarshal([]byte(expected.Details.ChangesetJSON), &wantPlan))
 
-		if diff := cmp.Diff(gotPlan, wantPlan, cmpopts.IgnoreFields(tfjson.Plan{}, "Timestamp")); diff != "" {
+		if diff := cmp.Diff(gotPlan, wantPlan, cmpopts.IgnoreFields(tfjson.Plan{}, "Timestamp", "FormatVersion")); diff != "" {
 			t.Logf("want: %+v", expected.Details.ChangesetJSON)
 			t.Logf("got: %+v", got.Details.ChangesetJSON)
 			t.Fatal(diff)
 		}
 	}
 }
+
+func loadJSONPlan(t *testing.T, fname string) string {
+	fname = filepath.FromSlash(fname)
+	jsonBytes := test.ReadFile(t, filepath.Dir(fname), filepath.Base(fname))
+	var plan tfjson.Plan
+	assert.NoError(t, json.Unmarshal(jsonBytes, &plan))
+	plan.TerraformVersion = terraformVersion
+	jsonNewBytes, err := json.Marshal(&plan)
+	assert.NoError(t, err)
+	return string(jsonNewBytes)
+}