Add support for fish completion (#1201)

Co-authored-by: Sascha Grunert <[email protected]>

Author: sayboras

Diff for: .goreleaser.yml

@@ -92,6 +92,8 @@ brews:
       (bash_completion/"golangci-lint").write output
       output = Utils.popen_read("#{bin}/golangci-lint completion zsh")
       (zsh_completion/"_golangci-lint").write output
+      output = Utils.popen_read("#{bin}/golangci-lint completion fish")
+      (fish_completion/"eksctl.fish").write output
       prefix.install_metafiles
     test: |
       system "#{bin}/golangci-lint --version"

Diff for: go.mod

@@ -45,7 +45,7 @@ require (
 	github.com/sirupsen/logrus v1.6.0
 	github.com/sonatard/noctx v0.0.1
 	github.com/sourcegraph/go-diff v0.6.0
-	github.com/spf13/cobra v1.0.0
+	github.com/spf13/cobra v1.0.1-0.20200916152758-7f8e83d9366a
 	github.com/spf13/pflag v1.0.5
 	github.com/spf13/viper v1.7.1
 	github.com/ssgreg/nlreturn/v2 v2.1.0

Diff for: go.sum

@@ -28,6 +28,13 @@ func (e *Executor) initCompletion() {
 		RunE:  e.executeZshCompletion,
 	}
 	completionCmd.AddCommand(zshCmd)
+
+	fishCmd := &cobra.Command{
+		Use:   "fish",
+		Short: "Output fish completion script",
+		RunE:  e.executeFishCompletion,
+	}
+	completionCmd.AddCommand(fishCmd)
 }
 
 func (e *Executor) executeBashCompletion(cmd *cobra.Command, args []string) error {
@@ -51,3 +58,12 @@ func (e *Executor) executeZshCompletion(cmd *cobra.Command, args []string) error
 
 	return nil
 }
+
+func (e *Executor) executeFishCompletion(cmd *cobra.Command, args []string) error {
+	err := cmd.Root().GenFishCompletion(os.Stdout, true)
+	if err != nil {
+		return errors.Wrap(err, "generate fish completion")
+	}
+
+	return nil
+}