Add actionable error codes (#33)

README.md

@@ -81,6 +81,16 @@ Use the `upgrade012` command to upgrade the blocks to 0.12:
 
 ![fmt](_docs/upgrade.png)
 
+### Exit codes
+
+To help usage of `terrafmt` in workflows, some commands will return actionable exit codes.
+
+If a Terraform parsing error is encountered in a block, the exit code is `2`.
+
+If the command `diff` with the `--check` flag enabled encounters a formatting difference, it will return `4`. If a file contains both blocks with parsing errors and a formatting difference, it will combine the exit codes to return `6`. These codes can be tested using bitwise checks.
+
+Otherwise, `terrafmt` will return `1` on an error.
+
 ## Development and Testing
 
 This project uses [Go Modules](https://github.com/golang/go/wiki/Modules) for dependency management.

cli/blocks_test.go

@@ -16,7 +16,7 @@ type block struct {
 	text    string
 }
 
-var testcases = []struct {
+var blocksTestcases = []struct {
 	name           string
 	sourcefile     string
 	lineCount      int
@@ -104,6 +104,45 @@ var testcases = []struct {
   bucket    = "tf-test-bucket-extra-space-%d"
 
   %s
+}`,
+			},
+		},
+	},
+	{
+		name:       "Go bad terraform",
+		sourcefile: "testdata/bad_terraform.go",
+		lineCount:  20,
+		expectedBlocks: []block{
+			{
+				endLine: 12,
+				text: `rrrrrresource "aws_s3_bucket" "rrrrrrr" {
+  bucket =    "tf-test-bucket"
+}`,
+			},
+			{
+				endLine: 19,
+				text: `resource "aws_s3_bucket" "unclosed" {
+  bucket =    "tf-test-bucket"`,
+			},
+		},
+	},
+	{
+		name:       "Go unsupported format verbs",
+		sourcefile: "testdata/unsupported_fmt.go",
+		lineCount:  21,
+		expectedBlocks: []block{
+			{
+				endLine: 20,
+				text: `resource "aws_s3_bucket" "multi-verb" {
+  bucket =    "tf-test-bucket"
+
+  tags = {
+    %[1]q =    %[2]q
+    Test  =  "${%[5]s.name}"
+    Name  =       "${%s.name}"
+    byte       = "${aws_acm_certificate.test.*.arn[%[2]d]}"
+    Data  =    "${data.%s.name}"
+  }
 }`,
 			},
 		},
@@ -171,7 +210,7 @@ var testcases = []struct {
 func TestCmdBlocksDefault(t *testing.T) {
 	t.Parallel()
 
-	for _, testcase := range testcases {
+	for _, testcase := range blocksTestcases {
 		testcase := testcase
 		t.Run(testcase.name, func(t *testing.T) {
 			t.Parallel()
@@ -210,7 +249,7 @@ func TestCmdBlocksDefault(t *testing.T) {
 func TestCmdBlocksVerbose(t *testing.T) {
 	t.Parallel()
 
-	for _, testcase := range testcases {
+	for _, testcase := range blocksTestcases {
 		testcase := testcase
 		t.Run(testcase.name, func(t *testing.T) {
 			t.Parallel()
@@ -239,7 +278,7 @@ func TestCmdBlocksVerbose(t *testing.T) {
 func TestCmdBlocksZeroTerminated(t *testing.T) {
 	t.Parallel()
 
-	for _, testcase := range testcases {
+	for _, testcase := range blocksTestcases {
 		t.Run(testcase.name, func(t *testing.T) {
 			t.Parallel()
 

cli/cmds.go

@@ -24,6 +24,13 @@ import (
 	"github.com/spf13/viper"
 )
 
+const (
+	ExitCodeNoError             = 0
+	ExitCodeMiscError           = 1
+	ExitCodeBlockParsingError   = 1 << 1
+	ExitCodeFormattingDiffError = 1 << 2
+)
+
 func Make() *cobra.Command {
 	root := &cobra.Command{
 		Use:           "terrafmt [fmt|diff|blocks|upgrade012]",
@@ -62,7 +69,7 @@ func Make() *cobra.Command {
 			verbose := viper.GetBool("verbose")
 
 			var errs *multierror.Error
-			var hasProcessingErrors bool
+			exitCode := ExitCodeNoError
 
 			for _, filename := range filenames {
 				br, err := formatFile(fs, log, filename, fmtCompat, fixFinishLines, verbose, cmd.InOrStdin(), cmd.OutOrStdout(), cmd.ErrOrStderr())
@@ -72,14 +79,14 @@ func Make() *cobra.Command {
 				}
 
 				if br.ErrorBlocks > 0 {
-					hasProcessingErrors = true
+					exitCode |= ExitCodeBlockParsingError
 				}
 			}
 			if errs != nil {
 				return errs
 			}
-			if hasProcessingErrors {
-				os.Exit(1)
+			if exitCode != ExitCodeNoError {
+				os.Exit(exitCode)
 			}
 
 			return nil
@@ -112,9 +119,8 @@ func Make() *cobra.Command {
 			if err != nil {
 				return err
 			}
-
 			if br.ErrorBlocks > 0 {
-				os.Exit(-1)
+				os.Exit(ExitCodeBlockParsingError)
 			}
 
 			return nil
@@ -144,8 +150,8 @@ func Make() *cobra.Command {
 			}
 
 			var errs *multierror.Error
-			var hasDiff bool
-			var hasProcessingErrors bool
+			check := viper.GetBool("check")
+			exitCode := ExitCodeNoError
 
 			for _, filename := range filenames {
 				br, fileDiff, err := diffFile(fs, log, filename, viper.GetBool("fmtcompat"), viper.GetBool("verbose"), cmd.InOrStdin(), cmd.OutOrStdout(), cmd.ErrOrStderr())
@@ -154,21 +160,17 @@ func Make() *cobra.Command {
 					continue
 				}
 				if br.ErrorBlocks > 0 {
-					hasProcessingErrors = true
+					exitCode |= ExitCodeBlockParsingError
 				}
-				if fileDiff {
-					hasDiff = true
+				if check && fileDiff {
+					exitCode |= ExitCodeFormattingDiffError
 				}
 			}
 			if errs != nil {
 				return errs
 			}
-
-			if viper.GetBool("check") && hasDiff {
-				os.Exit(1)
-			}
-			if hasProcessingErrors {
-				os.Exit(1)
+			if exitCode != ExitCodeNoError {
+				os.Exit(exitCode)
 			}
 
 			return nil