change isGenerated heuristic to match more generated files

As observed in #30, there's tools out there that don't comply 100% with
the referenced golang convention.

With this change, golangci-lint will skip some more of those generated
files.

Signed-off-by: Stephan Renatus <srenatus@chef.io>

pkg/result/processors/nolint.go

@@ -47,21 +47,26 @@ func (p *Nolint) Process(issues []result.Issue) ([]result.Issue, error) {
 }
 
 var (
-	genHdr = []byte("// Code generated ")
+	genHdr = []byte("// Code generated")
-	genFtr = []byte(" DO NOT EDIT.")
+	genFtr = []byte("DO NOT EDIT")
 )
 
-// isGenerated reports whether the source file is generated code
+// isGenerated reports whether the source file is generated code.
-// according the rules from https://golang.org/s/generatedcode.
+// Using a bit laxer rules than https://golang.org/s/generatedcode to
+// match more generated code.
 func isGenerated(src []byte) bool {
 	sc := bufio.NewScanner(bytes.NewReader(src))
+	var hdr, ftr bool
 	for sc.Scan() {
 		b := sc.Bytes()
-		if bytes.HasPrefix(b, genHdr) && bytes.HasSuffix(b, genFtr) && len(b) >= len(genHdr)+len(genFtr) {
+		if bytes.HasPrefix(b, genHdr) {
-			return true
+			hdr = true
+		}
+		if bytes.Contains(b, genFtr) {
+			ftr = true
 		}
 	}
-	return false
+	return hdr && ftr
 }
 
 func (p *Nolint) getOrCreateFileData(i *result.Issue) (*fileData, error) {

pkg/result/processors/nolint_test.go

@@ -37,13 +37,22 @@ func TestNolint(t *testing.T) {
 	processAssertSame(t, p, newNolintFileIssue(1, "golint")) // no directive
 }
 
-func TestNoIssuesInAutogeneratedFile(t *testing.T) {
+func TestNoIssuesInAutogeneratedFiles(t *testing.T) {
+	files := []string{
+		"nolint_autogenerated.go",
+		"nolint_autogenerated_alt_hdr.go",
+		"nolint_autogenerated_alt_hdr2.go",
+	}
+	for _, file := range files {
+		t.Run(file, func(t *testing.T) {
 			i := result.Issue{
 				Pos: token.Position{
-			Filename: filepath.Join("testdata", "nolint_autogenerated.go"),
+					Filename: filepath.Join("testdata", file),
 					Line:     4,
 				},
 			}
 			p := NewNolint(token.NewFileSet())
 			processAssertEmpty(t, p, i)
+		})
+	}
 }

pkg/result/processors/testdata/nolint_autogenerated_alt_hdr.go

@@ -0,0 +1,6 @@
+// Code generated by protoc-gen-foo
+// source: bar.proto
+// DO NOT EDIT!!!
+package testdata
+
+var v int

pkg/result/processors/testdata/nolint_autogenerated_alt_hdr2.go

@@ -0,0 +1,8 @@
+// Code generated by go-bindata.
+// sources:
+// bar.baz
+// x/y.z
+// DO NOT EDIT!
+package testdata
+
+var v int