feat: languages list command (#1114)

* feat: languages list command

* corrections

cmd/invoke.go

@@ -22,7 +22,7 @@ func NewInvokeCmd(newClient ClientFactory) *cobra.Command {
 		Short: "Invoke a Function",
 		Long: `
 NAME
-	{{.Name}} invoke - Invoke a Function.
+	{{.Name}} invoke - test a Function by invoking it with test data
 
 SYNOPSIS
 	{{.Name}} invoke [-t|--target] [-f|--format]

cmd/languages.go

@@ -0,0 +1,123 @@
+package cmd
+
+import (
+	"encoding/json"
+	"fmt"
+	"os"
+
+	"github.com/ory/viper"
+	"github.com/spf13/cobra"
+
+	fn "knative.dev/kn-plugin-func"
+)
+
+func NewLanguagesCmd(newClient ClientFactory) *cobra.Command {
+	cmd := &cobra.Command{
+		Use:   "languages",
+		Short: "Languages",
+		Long: `
+NAME
+	{{.Name}} languages - list available language runtimes.
+
+SYNOPSIS
+	{{.Name}} languages [--json] [-r|--repository]
+
+DESCRIPTION
+	List the language runtimes that are currently available.
+	This includes embedded (included) language runtimes as well as any installed
+	via the 'repositories add' command.
+
+	Installed repositories are by default located at ~/.func/repositories
+	($XDG_CONFIG_HOME/.func/repositories).  This can be overridden with
+	$FUNC_REPOSITORIES_PATH.
+
+	To specify a URI of a single, specific repository for which languages
+	should be displayed, use the --repository flag.
+	
+	To see templates available for a given language, see the 'templates' command.
+
+
+EXAMPLES
+
+	o Show a list of all available language runtimes
+	  $ {{.Name}} languages
+
+	o Return a list of all language runtimes in JSON
+	  $ {{.Name}} languages --json
+
+	o Return language runtimes in a specific repository
+		$ {{.Name}} languages --repository=https://github.com/boson-project/func-templates
+`,
+		SuggestFor: []string{"language", "runtime", "runtimes", "lnaguages", "languagse",
+			"panguages", "manguages", "kanguages", "lsnguages", "lznguages"},
+		PreRunE: bindEnv("json", "repository"),
+	}
+
+	cmd.Flags().BoolP("json", "", false, "Set output to JSON format: $FUNC_JSON)")
+	cmd.Flags().StringP("repository", "r", "", "URI to a specific repository to consider (Env: $FUNC_REPOSITORY)")
+
+	cmd.SetHelpFunc(defaultTemplatedHelp)
+
+	cmd.RunE = func(cmd *cobra.Command, args []string) error {
+		return runLanguages(cmd, args, newClient)
+	}
+
+	return cmd
+}
+
+func runLanguages(cmd *cobra.Command, args []string, newClient ClientFactory) (err error) {
+	cfg, err := newLanguagesConfig(newClient)
+	if err != nil {
+		return
+	}
+
+	client, done := newClient(ClientConfig{Verbose: cfg.Verbose},
+		fn.WithRepository(cfg.Repository),             // Use exactly this repo OR
+		fn.WithRepositoriesPath(cfg.RepositoriesPath)) // Path on disk to installed repos
+	defer done()
+
+	runtimes, err := client.Runtimes()
+	if err != nil {
+		return
+	}
+
+	if cfg.JSON {
+		var s []byte
+		s, err = json.MarshalIndent(runtimes, "", "  ")
+		if err != nil {
+			return
+		}
+		fmt.Fprintln(cmd.OutOrStdout(), string(s))
+	} else {
+		for _, runtime := range runtimes {
+			fmt.Fprintln(cmd.OutOrStdout(), runtime)
+		}
+	}
+	return
+}
+
+type languagesConfig struct {
+	Verbose          bool
+	Repository       string // Consider only a specific repository (URI)
+	RepositoriesPath string // Override location on disk of "installed" repos
+	JSON             bool   // output as JSON
+}
+
+func newLanguagesConfig(newClient ClientFactory) (cfg languagesConfig, err error) {
+	// Repositories Path
+	// Not exposed as a flag due to potential confusion with the more likely
+	// "repository" flag, but still available as an environment variable
+	repositoriesPath := os.Getenv("FUNC_REPOSITORIES_PATH")
+	if repositoriesPath == "" { // if no env var provided
+		repositoriesPath = fn.New().RepositoriesPath() // default to ~/.config/func/repositories
+	}
+
+	cfg = languagesConfig{
+		Verbose:          viper.GetBool("verbose"),
+		Repository:       viper.GetString("repository"),
+		RepositoriesPath: repositoriesPath,
+		JSON:             viper.GetBool("json"),
+	}
+
+	return
+}

cmd/languages_test.go

@@ -0,0 +1,62 @@
+package cmd
+
+import (
+	"testing"
+
+	fn "knative.dev/kn-plugin-func"
+	. "knative.dev/kn-plugin-func/testing"
+)
+
+// TestLanguages_Default ensures that the default behavior of listing
+// all supported languages is to print a plain text list of all the builtin
+// language runtimes.
+func TestLanguages_Default(t *testing.T) {
+	defer WithEnvVar(t, "XDG_CONFIG_HOME", t.TempDir())() // ignore user-added
+	buf := piped(t)                                       // gather output
+	cmd := NewLanguagesCmd(NewClientFactory(func() *fn.Client {
+		return fn.New()
+	}))
+	if err := cmd.Execute(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := `go
+node
+python
+quarkus
+rust
+springboot
+typescript`
+	output := buf()
+	if output != expected {
+		t.Fatalf("expected:\n'%v'\ngot:\n'%v'\n", expected, output)
+	}
+}
+
+// TestLanguages_JSON ensures that listing languages in --json format returns
+// builtin languages as a JSON array.
+func TestLanguages_JSON(t *testing.T) {
+	defer WithEnvVar(t, "XDG_CONFIG_HOME", t.TempDir())() // ignore user-added
+	buf := piped(t)                                       // gather output
+	cmd := NewLanguagesCmd(NewClientFactory(func() *fn.Client {
+		return fn.New()
+	}))
+	cmd.SetArgs([]string{"--json"})
+	if err := cmd.Execute(); err != nil {
+		t.Fatal(err)
+	}
+
+	expected := `[
+  "go",
+  "node",
+  "python",
+  "quarkus",
+  "rust",
+  "springboot",
+  "typescript"
+]`
+	output := buf()
+	if output != expected {
+		t.Fatalf("expected:\n%v\ngot:\n%v\n", expected, output)
+	}
+}