Add ability to ignore packages

By passing the `--ignore` flag to go-apidiff it is now possible to
ignore incompatible changes in a list of packages. This flag can be
specified multiple times.

This is passed via the `ignore-list` input parameter in the github
action and must be specified as a comma-separated list.

Fixes joelanford#35

README.md

@@ -22,6 +22,10 @@ Version of go-apidiff to use (default: `latest`)
 
 Compare exported API differences in the imports of the repo (default: `false`)
 
+#### `ignore-list`
+
+Comma-separated list of packages prefixes to ignore (default: `''`)
+
 #### `print-compatible`
 
 Print compatible API changes (default: `true`)
@@ -80,6 +84,7 @@ Usage:
 Flags:
       --compare-imports    Compare exported API differences of the imports in the repo.
   -h, --help               help for go-apidiff
+  -i, --ignore strings     Ignore packages starting with prefix. Can be repeated.
       --print-compatible   Print compatible API changes
       --repo-path string   Path to root of git repository to compare (default "/home/myuser/myproject")
 ```

action.yml

@@ -24,6 +24,10 @@ inputs:
     description: 'Path to root of git repository to compare'
     required: false
     default: '.'
+  ignore-list:
+    description: 'Comma-separated list of packages prefixes to ignore'
+    required: false
+    default: ''
 outputs:
   semver-type:
     description: "Returns the type (patch, minor, major) of the sementic version that would be required if producing a release."
@@ -48,7 +52,7 @@ runs:
         set -x
         GOPATH=$(go env GOPATH)
         set +e
-        OUTPUT=$($GOPATH/bin/go-apidiff ${{ inputs.base-ref }} --compare-imports=${{ inputs.compare-imports }} --print-compatible=${{ inputs.print-compatible }} --repo-path=${{ inputs.repo-path }})
+        OUTPUT=$($GOPATH/bin/go-apidiff ${{ inputs.base-ref }} --compare-imports=${{ inputs.compare-imports }} --print-compatible=${{ inputs.print-compatible }} --repo-path=${{ inputs.repo-path }} --ignore=${{ inputs.ignore-list }} )
         GOAPIDIFF_RC=$?
         set -e
         if [ $GOAPIDIFF_RC -eq 0 ]; then

main.go

@@ -93,6 +93,7 @@ and HEAD is used for newCommit."`,
 	cmd.Flags().StringVar(&opts.RepoPath, "repo-path", cwd, "Path to root of git repository to compare")
 	cmd.Flags().BoolVar(&opts.CompareImports, "compare-imports", false, "Compare exported API differences of the imports in the repo. ")
 	cmd.Flags().BoolVar(&printCompatible, "print-compatible", false, "Print compatible API changes")
+	cmd.Flags().StringSliceVarP(&opts.IgnoreList, "ignore", "i", []string{}, "Ignore packages starting with prefix. Can be repeated.")
 
 	return cmd
 }

pkg/diff/run.go

@@ -37,6 +37,7 @@ type Options struct {
 	OldCommit      string
 	NewCommit      string
 	CompareImports bool
+	IgnoreList     []string
 }
 
 func Run(opts Options) (*Diff, error) {
@@ -97,12 +98,12 @@ func Run(opts Options) (*Diff, error) {
 		}
 	}()
 
-	selfOld, importsOld, err := getPackages(*wt, *oldHash)
+	selfOld, importsOld, err := getPackages(*wt, *oldHash, opts.IgnoreList)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get packages from old commit %q (%s): %w", opts.OldCommit, oldHash, err)
 	}
 
-	selfNew, importsNew, err := getPackages(*wt, *newHash)
+	selfNew, importsNew, err := getPackages(*wt, *newHash, opts.IgnoreList)
 	if err != nil {
 		return nil, fmt.Errorf("failed to get packages from new commit %q (%s): %w", opts.NewCommit, newHash, err)
 	}
@@ -192,7 +193,16 @@ func getHashes(repo *git.Repository, oldRev, newRev plumbing.Revision) (*plumbin
 	return oldCommitHash, newCommitHash, nil
 }
 
-func getPackages(wt git.Worktree, hash plumbing.Hash) (map[string]*packages.Package, map[string]*packages.Package, error) {
+func ignorePackage(pkg string, ignoreList []string) bool {
+	for _, ignore := range ignoreList {
+		if strings.HasPrefix(pkg, ignore) {
+			return true
+		}
+	}
+	return false
+}
+
+func getPackages(wt git.Worktree, hash plumbing.Hash, ignoreList []string) (map[string]*packages.Package, map[string]*packages.Package, error) {
 	if err := wt.Checkout(&git.CheckoutOptions{Hash: hash, Force: true}); err != nil {
 		return nil, nil, err
 	}
@@ -222,7 +232,7 @@ func getPackages(wt git.Worktree, hash plumbing.Hash) (map[string]*packages.Pack
 	importPkgs := make(map[string]*packages.Package)
 	for _, pkg := range pkgs {
 		// skip internal packages since they do not contain public APIs
-		if strings.HasSuffix(pkg.PkgPath, "/internal") || strings.Contains(pkg.PkgPath, "/internal/") {
+		if strings.HasSuffix(pkg.PkgPath, "/internal") || strings.Contains(pkg.PkgPath, "/internal/") || ignorePackage(pkg.PkgPath, ignoreList) {
 			continue
 		}
 		selfPkgs[pkg.PkgPath] = pkg