Ability to optionally ignore generated files (#8)

This gives a user the ability to optionally ignore files generated by the `go generate` command. 

Fixes #7

Author: jasonhancock

README.md

@@ -29,14 +29,18 @@ Note that impi does not support regenerating the files, only warns of infraction
 ## Usage
 ```
 go get -u github.com/pavius/impi/cmd/impi
-impi [--local <local import prefix>] --scheme <scheme> <packages>
+impi [--local <local import prefix>] [--ignore-generated=<bool>] --scheme <scheme> <packages>
 ```
 
 [nuclio](https://github.com/nuclio/nuclio) uses impi as follows:
 ```
 impi --local github.com/nuclio/nuclio/ --scheme stdLocalThirdParty ./cmd/... ./pkg/...
 ```
 
+## Ignoring Generated Files
+
+Set `--ignore-generated=true` to ignore files that have been generated by `go generate`.
+
 ## Supported schemes
 
 impi currently supports the following schemes:

cmd/impi/main.go

@@ -15,12 +15,12 @@ type consoleErrorReporter struct{}
 type stringArrayFlags []string
 
 func (saf *stringArrayFlags) String() string {
-    return strings.Join(*saf, ",")
+	return strings.Join(*saf, ",")
 }
 
 func (saf *stringArrayFlags) Set(value string) error {
-    *saf = append(*saf, value)
-    return nil
+	*saf = append(*saf, value)
+	return nil
 }
 
 func (cer *consoleErrorReporter) Report(err impi.VerificationError) {
@@ -42,6 +42,7 @@ func run() error {
 
 	var localPrefix = flag.String("local", "", "prefix of the local repository")
 	var scheme = flag.String("scheme", "", "verification scheme to enforce. one of stdLocalThirdParty/stdThirdPartyLocal")
+	var ignoreGenerated = flag.Bool("ignore-generated", false, "ignore files generated by 'go generate'")
 
 	var skipPaths stringArrayFlags
 	flag.Var(&skipPaths, "skip", "paths to skip (regex)")
@@ -67,10 +68,11 @@ func run() error {
 		}
 
 		err = impiInstance.Verify(rootPath, &impi.VerifyOptions{
-			SkipTests:     false,
-			LocalPrefix:   *localPrefix,
-			Scheme:        verificationScheme,
-			SkipPaths:     skipPaths,
+			SkipTests:       false,
+			LocalPrefix:     *localPrefix,
+			Scheme:          verificationScheme,
+			SkipPaths:       skipPaths,
+			IgnoreGenerated: *ignoreGenerated,
 		}, &consoleErrorReporter{})
 
 		if err != nil {

impi.go

@@ -5,10 +5,10 @@ import (
 	"io/ioutil"
 	"os"
 	"path"
+	"regexp"
 	"strings"
 
 	"github.com/kisielk/gotool"
-	"regexp"
 )
 
 // Impi is a single instance that can perform verification on a path
@@ -49,10 +49,11 @@ const (
 
 // VerifyOptions specifies how to perform verification
 type VerifyOptions struct {
-	SkipTests   bool
-	Scheme      ImportGroupVerificationScheme
-	LocalPrefix string
-	SkipPaths   []string
+	SkipTests       bool
+	Scheme          ImportGroupVerificationScheme
+	LocalPrefix     string
+	SkipPaths       []string
+	IgnoreGenerated bool
 }
 
 // VerificationError holds an error and a file path on which the error occurred

verifier.go

@@ -7,11 +7,16 @@ import (
 	"go/parser"
 	"go/token"
 	"io"
+	"io/ioutil"
 	"reflect"
+	"regexp"
 	"sort"
 	"strings"
 )
 
+// This regex is to appear in generated code.
+var generatedRegex = regexp.MustCompile("// Code generated .* DO NOT EDIT\\.")
+
 type verifier struct {
 	verifyOptions *VerifyOptions
 }
@@ -63,6 +68,23 @@ func newVerifier() (*verifier, error) {
 func (v *verifier) verify(sourceFileReader io.ReadSeeker, verifyOptions *VerifyOptions) error {
 	v.verifyOptions = verifyOptions
 
+	if verifyOptions.IgnoreGenerated {
+		// The line specifying that the code was generated can be found anywhere
+		// within a file. In practice, it is the first line.
+		fileContents, err := ioutil.ReadAll(sourceFileReader)
+		if err != nil {
+			return err
+		}
+
+		if generatedRegex.Match(fileContents) {
+			return nil
+		}
+
+		if _, err := sourceFileReader.Seek(0, 0); err != nil {
+			return err
+		}
+	}
+
 	// get lines on which imports start and end
 	importLineNumbers, err := v.getImportPos(sourceFileReader)
 	if err != nil {

verifier_test.go

@@ -2,6 +2,7 @@ package impi
 
 import (
 	"strings"
+	"testing"
 
 	"github.com/stretchr/testify/suite"
 )
@@ -51,3 +52,76 @@ func (s *VerifierTestSuite) verifyTestCases(verificationTestCases []verification
 		}
 	}
 }
+
+type IgnoreGeneratedFileTestSuite struct {
+	VerifierTestSuite
+}
+
+func (s *IgnoreGeneratedFileTestSuite) SetupSuite() {
+	s.options.Scheme = ImportGroupVerificationSchemeStdLocalThirdParty
+	s.options.LocalPrefix = "github.com/pavius/impi"
+	s.options.IgnoreGenerated = true
+}
+
+func (s *IgnoreGeneratedFileTestSuite) TestValidAllGroups() {
+	verificationTestCases := []verificationTestCase{
+		{
+			name: "invalid order, but ignore generated files",
+			contents: `// Code generated by foo; DO NOT EDIT.
+// github.com/example/foo
+
+package fixtures
+
+import (
+    "fmt"
+    "os"
+    "github.com/example/foo"
+    "path"
+)
+`,
+		},
+	}
+	s.verifyTestCases(verificationTestCases)
+}
+
+func TestIgnoreGeneratedFileTestSuite(t *testing.T) {
+	suite.Run(t, new(IgnoreGeneratedFileTestSuite))
+}
+
+type NotIgnoreGeneratedFileTestSuite struct {
+	VerifierTestSuite
+}
+
+func (s *NotIgnoreGeneratedFileTestSuite) SetupSuite() {
+	s.options.Scheme = ImportGroupVerificationSchemeStdLocalThirdParty
+	s.options.LocalPrefix = "github.com/pavius/impi"
+}
+
+func (s *NotIgnoreGeneratedFileTestSuite) TestValidAllGroups() {
+
+	verificationTestCases := []verificationTestCase{
+		{
+			name: "invalid order, not ignoring generated files",
+			contents: `// Code generated by foo; DO NOT EDIT.
+// github.com/example/foo
+
+package fixtures
+
+import (
+    "fmt"
+    "os"
+    "github.com/example/foo"
+    "path"
+)
+`,
+			expectedErrorStrings: []string{
+				"Imports of different types are not allowed in the same group",
+			},
+		},
+	}
+	s.verifyTestCases(verificationTestCases)
+}
+
+func TestNotIgnoreGeneratedFileTestSuite(t *testing.T) {
+	suite.Run(t, new(NotIgnoreGeneratedFileTestSuite))
+}