purepkg - pure packages

When developing in Go it can be desirable at times to limit the imports in a package. For reasons like:

• Avoid the likelihood of future circular dependencies when you have a certain package structure in mind.
• Having the intention to move the package to its own repository later as an independent library.
• Enforcement of a certain package architecture.
• Prevent accidently importing the wrong package: think of math/rand instead of crypto/rand in cryptographic code.
• Caring about the purity of a package, eg. only using the standard library.

purepkg can help to achieve that by verifying that only allowed packages are imported.

Installation

You can install purepkg directly from the main branch with go install github.com/the/purepkg. Or run it directly by invoking go run github.com/the/purepkg.

Usage

purepkg [-v] [-stdlib] [-notest] [-allow pkg1,pkg2,...] <package>

Options:
  -allow packages
    	comma separated list of allowed packages
  -notest
    	ignore tests
  -stdlib
    	include all standard library packages
  -v    verbose output

When no unallowed package is found purepkg exits with exit code 0. Otherwise it will exit with 2 which can be useful to abort a build process or checks executed in a CI/CD pipeline. By default test code is included. Adding the -notest argument ignores the tests.

Examples

$ purepkg -stdlib github.com/the/purepkg

package github.com/the/purepkg
  ✗ import golang.org/x/tools/go/packages

$ purepkg -v -stdlib -allow "golang.org/*" github.com/the/purepkg

package github.com/the/purepkg
  ✔ import log
  ✔ import os
  ✔ import strings
  ✔ import flag
  ✔ import fmt
  ✔ import golang.org/x/tools/go/packages

$ purepkg -v -stdlib -allow "golang.org/x/text*" golang.org/x/text/language/...

package golang.org/x/text/language
  ✔ import sort
  ✔ import strconv
  ✔ import strings
  ✔ import errors
  ✔ import fmt
  ✔ import golang.org/x/text/internal/language
  ✔ import golang.org/x/text/internal/language/compact
package golang.org/x/text/language/display
  ✔ import sort
  ✔ import strings
  ✔ import fmt
  ✔ import golang.org/x/text/internal/format
  ✔ import golang.org/x/text/language