Truncate pre-release version before comparing

The hashicorp/go-version returns false when comparing pre-releases, for
example 1.6.0-rc1 >= 0.13. This is counter-intuitive for determining the
presence or absence of a feature, so remove the pre-release information
before comparing.

tfexec/terraform_providers_test.go

@@ -2,11 +2,8 @@ package tfexec
 
 import (
 	"context"
-	"fmt"
 	"reflect"
 	"testing"
-
-	"github.com/hashicorp/go-version"
 )
 
 var providersStdout = `
@@ -100,18 +97,13 @@ resource "null_resource" "bar" {}
 		t.Fatalf("failed to run terraform providers: %s", err)
 	}
 
-	v, err := terraformCLI.Version(context.Background())
-	if err != nil {
-		t.Fatalf("unexpected version error: %s", err)
-	}
-
-	constraints, err := version.NewConstraint(fmt.Sprintf(">= %s", MinimumTerraformVersionForStateReplaceProvider))
+	supportsStateReplaceProvider, _, err := terraformCLI.SupportsStateReplaceProvider(context.Background())
 	if err != nil {
-		t.Fatalf("unexpected version constraint error: %s", err)
+		t.Fatalf("failed to determine if Terraform version supports state replace-provider: %s", err)
 	}
 
 	want := providersStdout
-	if !constraints.Check(v) {
+	if !supportsStateReplaceProvider {
 		want = legacyProvidersStdout
 	}
 

tfexec/terraform_state_replace_provider.go

@@ -34,7 +34,12 @@ func (c *terraformCLI) SupportsStateReplaceProvider(ctx context.Context) (bool,
 		return false, constraints, err
 	}
 
-	if !constraints.Check(v) {
+	ver, err := truncatePreReleaseVersion(v)
+	if err != nil {
+		return false, constraints, err
+	}
+
+	if !constraints.Check(ver) {
 		return false, constraints, nil
 	}
 

tfexec/terraform_version.go

@@ -4,6 +4,7 @@ import (
 	"context"
 	"fmt"
 	"regexp"
+	"strings"
 
 	"github.com/hashicorp/go-version"
 )
@@ -29,3 +30,24 @@ func (c *terraformCLI) Version(ctx context.Context) (*version.Version, error) {
 
 	return version, nil
 }
+
+// truncatePreReleaseVersion is a helper function that removes
+// pre-release information.
+// The hashicorp/go-version returns false when comparing pre-releases, for
+// example 1.6.0-rc1 >= 0.13. This is counter-intuitive for determining the
+// presence or absence of a feature, so remove the pre-release information
+// before comparing.
+func truncatePreReleaseVersion(v *version.Version) (*version.Version, error) {
+	if v.Prerelease() == "" {
+		return v, nil
+	}
+
+	vs, _, _ := strings.Cut(v.String(), "-")
+
+	ver, err := version.NewVersion(vs)
+	if err != nil {
+		return nil, err
+	}
+
+	return ver, nil
+}