added version contraint liniting

.gomodguard.yaml

@@ -2,7 +2,7 @@ allowed:
   modules:                                                      # List of allowed modules
     - gopkg.in/yaml.v2
     - github.com/go-xmlfmt/xmlfmt
-    - github.com/phayes/checkstyle
+    - github.com/Masterminds/semver
   domains:                                                      # List of allowed module domains
     - golang.org
 
@@ -15,4 +15,13 @@ blocked:
     - github.com/mitchellh/go-homedir:
         recommendations:
           - github.com/ryancurrah/gomodguard
-        reason: "testing if the linted module is not blocked when it is recommended"
+        reason: "testing if the current/linted module is not blocked when it is recommended"
+    - github.com/phayes/checkstyle:
+        recommendations:
+          - github.com/someother/module
+        reason: "testing if module is blocked with recommendation"
+
+  versions:
+    - github.com/mitchellh/go-homedir:
+        version: "<= 1.1.0"
+        reason: "testing if blocked version constraint works."

README.md

@@ -20,6 +20,8 @@ Alternative modules can be optionally recommended in the blocked modules list.
 
 If the linted module imports a blocked module but the linted module is in the recommended modules list the blocked module is ignored. Usually, this means the linted module wraps that blocked module for use by other modules, therefore the import of the blocked module should not be blocked.
 
+Version constraints can be specified for modules as well which lets you block new or old versions of modules or specific versions.
+
 Results are printed to `stdout`.
 
 Logging statements are printed to `stderr`.
@@ -44,6 +46,10 @@ blocked:
         recommendations:                                        # Recommended modules that should be used instead (Optional)
           - golang.org/x/mod                           
         reason: "`mod` is the official go.mod parser library."  # Reason why the recommended module should be used (Optional)
+  versions:                                                     # List of blocked module version constraints.
+    - github.com/mitchellh/go-homedir:                          # Blocked module with version constraint.
+        version: "<= 1.1.0"                                     # Version constraint, see https://github.com/Masterminds/semver#basic-comparisons.
+        reason: "testing if blocked version constraint works."  # Reason why the version constraint exists.
 ```
 
 ## Usage
@@ -54,17 +60,22 @@ Usage: gomodguard <file> [files...]
 Also supports package syntax but will use it in relative path, i.e. ./pkg/...
 Flags:
   -f string
-        Report results to the specified file. A report type must also be specified
+    	Report results to the specified file. A report type must also be specified
   -file string
 
-  -h    Show this help text
+  -h	Show this help text
   -help
 
-  -n    Don't lint test files
+  -i int
+    	Exit code when issues were found (default 2)
+  -issues-exit-code int 
+      (default 2)
+
+  -n	Don't lint test files
   -no-test
 
   -r string
-        Report results to one of the following formats: checkstyle. A report file destination must also be specified
+    	Report results to one of the following formats: checkstyle. A report file destination must also be specified
   -report string
 ```
 

cmd.go

@@ -24,19 +24,19 @@ const (
 var (
 	configFile           = ".gomodguard.yaml"
 	logger               = log.New(os.Stderr, "", 0)
-	lintErrorRC          = 2
 	errFindingConfigFile = fmt.Errorf("could not find config file")
 )
 
-// Run the gomodguard linter.
-func Run() {
+// Run the gomodguard linter. Returns the exit code to use.
+func Run() int {
 	var (
-		args       []string
-		help       bool
-		noTest     bool
-		report     string
-		reportFile string
-		cwd, _     = os.Getwd()
+		args           []string
+		help           bool
+		noTest         bool
+		report         string
+		reportFile     string
+		issuesExitCode int
+		cwd, _         = os.Getwd()
 	)
 
 	flag.BoolVar(&help, "h", false, "Show this help text")
@@ -47,13 +47,15 @@ func Run() {
 	flag.StringVar(&report, "report", "", "")
 	flag.StringVar(&reportFile, "f", "", "Report results to the specified file. A report type must also be specified")
 	flag.StringVar(&reportFile, "file", "", "")
+	flag.IntVar(&issuesExitCode, "i", 2, "Exit code when issues were found")
+	flag.IntVar(&issuesExitCode, "issues-exit-code", 2, "")
 	flag.Parse()
 
 	report = strings.TrimSpace(strings.ToLower(report))
 
 	if help {
 		showHelp()
-		return
+		return 0
 	}
 
 	if report != "" && report != "checkstyle" {
@@ -99,8 +101,10 @@ func Run() {
 	}
 
 	if len(results) > 0 {
-		os.Exit(lintErrorRC)
+		return issuesExitCode
 	}
+
+	return 0
 }
 
 // GetConfig from YAML file.
@@ -180,7 +184,7 @@ func GetFilteredFiles(cwd string, skipTests bool, args []string) []string {
 
 // showHelp text for command line.
 func showHelp() {
-	helpText := `Usage: gomodguard <file> [foundFiles...]
+	helpText := `Usage: gomodguard <file> [files...]
 Also supports package syntax but will use it in relative path, i.e. ./pkg/...
 Flags:`
 	fmt.Println(helpText)

cmd/gomodguard/main.go

@@ -1,9 +1,11 @@
 package main
 
 import (
+	"os"
+
 	"github.com/ryancurrah/gomodguard"
 )
 
 func main() {
-	gomodguard.Run()
+	os.Exit(gomodguard.Run())
 }

cmd_test.go

@@ -7,5 +7,10 @@ import (
 )
 
 func TestCmdRun(t *testing.T) {
-	gomodguard.Run()
+	wantExitCode := 2
+	exitCode := gomodguard.Run()
+
+	if exitCode != wantExitCode {
+		t.Errorf("got exit code '%d' want '%d'", exitCode, wantExitCode)
+	}
 }

go.mod

@@ -3,6 +3,7 @@ module github.com/ryancurrah/gomodguard
 go 1.14
 
 require (
+	github.com/Masterminds/semver v1.5.0
 	github.com/go-xmlfmt/xmlfmt v0.0.0-20191208150333-d5b6f63a941b
 	github.com/mitchellh/go-homedir v1.1.0
 	github.com/phayes/checkstyle v0.0.0-20170904204023-bfd46e6a821d

go.sum

@@ -1,3 +1,5 @@
+github.com/Masterminds/semver v1.5.0 h1:H65muMkzWKEuNDnfl9d70GUjFniHKHRbFPGBuZ3QEww=
+github.com/Masterminds/semver v1.5.0/go.mod h1:MB6lktGJrhw8PrUyiEoblNEGEQ+RzHPF078ddwwvV3Y=
 github.com/go-xmlfmt/xmlfmt v0.0.0-20191208150333-d5b6f63a941b h1:khEcpUM4yFcxg4/FHQWkvVRmgijNXRfzkIDHh23ggEo=
 github.com/go-xmlfmt/xmlfmt v0.0.0-20191208150333-d5b6f63a941b/go.mod h1:aUCEOzzezBEjDBbFBoSiya/gduyIiWYRP6CnSFIV8AM=
 github.com/mitchellh/go-homedir v1.1.0 h1:lukF9ziXFxDFPkA1vsr5zpc1XuPDn/wFntq5mG+4E0Y=