Add Backend() helper

Author: wata727

helper/runner.go

@@ -135,6 +135,42 @@ func (r *Runner) WalkResources(resourceType string, walker func(*terraform.Resou
 	return nil
 }
 
+// Backend returns the terraform backend configuration.
+func (r *Runner) Backend() (*terraform.Backend, error) {
+	for _, file := range r.Files {
+		tfcfg, _, diags := file.Body.PartialContent(&hcl.BodySchema{
+			Blocks: []hcl.BlockHeaderSchema{
+				{Type: "terraform"},
+			},
+		})
+		if diags.HasErrors() {
+			return nil, diags
+		}
+
+		for _, block := range tfcfg.Blocks {
+			backendCfg, _, diags := block.Body.PartialContent(&hcl.BodySchema{
+				Blocks: []hcl.BlockHeaderSchema{
+					{Type: "backend", LabelNames: []string{"type"}},
+				},
+			})
+			if diags.HasErrors() {
+				return nil, diags
+			}
+
+			for _, backendBlock := range backendCfg.Blocks {
+				return &terraform.Backend{
+					Type:      backendBlock.Labels[0],
+					TypeRange: backendBlock.LabelRanges[0],
+					Config:    backendBlock.Body,
+					DeclRange: backendBlock.DefRange,
+				}, nil
+			}
+		}
+	}
+
+	return nil, nil
+}
+
 // EvaluateExpr returns a value of the passed expression.
 // Note that there is no evaluation, no type conversion, etc.
 func (r *Runner) EvaluateExpr(expr hcl.Expression, ret interface{}) error {

helper/runner_test.go

@@ -11,6 +11,12 @@ import (
 	"github.com/terraform-linters/tflint-plugin-sdk/tflint"
 )
 
+func Test_satisfyRunnerInterface(t *testing.T) {
+	var runner tflint.Runner
+	runner = TestRunner(t, map[string]string{})
+	runner.EnsureNoError(nil, func() error { return nil })
+}
+
 func Test_WalkResourceAttributes(t *testing.T) {
 	src := `
 resource "aws_instance" "foo" {
@@ -309,6 +315,49 @@ func parseExpression(t *testing.T, src string, filename string, pos hcl.Pos) hcl
 	return expr
 }
 
+func Test_Backend(t *testing.T) {
+	src := `
+terraform {
+  backend "s3" {
+    bucket = "mybucket"
+    key    = "path/to/my/key"
+    region = "us-east-1"
+  }
+}`
+
+	runner := TestRunner(t, map[string]string{"main.tf": src})
+
+	backend, err := runner.Backend()
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	expected := &terraform.Backend{
+		Type:      "s3",
+		TypeRange: hcl.Range{Filename: "main.tf", Start: hcl.Pos{Line: 3, Column: 11}, End: hcl.Pos{Line: 3, Column: 15}},
+		Config: parseBody(
+			t,
+			`bucket = "mybucket"
+    key    = "path/to/my/key"
+    region = "us-east-1"`,
+			"main.tf",
+			hcl.Pos{Line: 4, Column: 5},
+			hcl.Range{Filename: "main.tf", Start: hcl.Pos{Line: 3, Column: 16}, End: hcl.Pos{Line: 7, Column: 4}},
+			hcl.Range{Filename: "main.tf", Start: hcl.Pos{Line: 7, Column: 4}, End: hcl.Pos{Line: 7, Column: 4}},
+		),
+		DeclRange: hcl.Range{Filename: "main.tf", Start: hcl.Pos{Line: 3, Column: 3}, End: hcl.Pos{Line: 3, Column: 15}},
+	}
+
+	opts := cmp.Options{
+		cmpopts.IgnoreFields(hclsyntax.LiteralValueExpr{}, "Val"),
+		cmpopts.IgnoreFields(hcl.Pos{}, "Byte"),
+		cmpopts.IgnoreUnexported(hclsyntax.Body{}),
+	}
+	if !cmp.Equal(expected, backend, opts...) {
+		t.Fatalf("Diff: %s", cmp.Diff(expected, backend, opts...))
+	}
+}
+
 func Test_EvaluateExpr(t *testing.T) {
 	src := `
 resource "aws_instance" "foo" {