plugins: Add an echo plugin for testing the plugin mechanism

plugins/jk-plugin-echo/main.go

@@ -0,0 +1,41 @@
+package main
+
+import (
+	"os"
+
+	"github.com/hashicorp/go-hclog"
+	"github.com/hashicorp/go-plugin"
+
+	"github.com/jkcfg/jk/pkg/plugin/renderer"
+)
+
+// Echo outputs its input.
+type Echo struct {
+	log hclog.Logger
+}
+
+// Render implements renderer.Renderer.
+func (h *Echo) Render(input []byte) ([]byte, error) {
+	h.log.Debug("debug message from echo plugin")
+	return input, nil
+}
+
+func main() {
+	logger := hclog.New(&hclog.LoggerOptions{
+		Level:  hclog.Info,
+		Output: os.Stderr,
+	})
+
+	r := &Echo{
+		log: logger,
+	}
+	// pluginMap is the map of plugins we can dispense.
+	var pluginMap = map[string]plugin.Plugin{
+		"renderer": &renderer.Plugin{Impl: r},
+	}
+
+	plugin.Serve(&plugin.ServeConfig{
+		HandshakeConfig: renderer.RendererV1,
+		Plugins:         pluginMap,
+	})
+}

tests/echo.json

@@ -0,0 +1,7 @@
+{
+  "name": "echo",
+  "version": "0.1.0",
+  "binaries": {
+    "linux-amd64": "jk-plugin-echo"
+  }
+}

tests/test-plugin-echo.js

@@ -0,0 +1,4 @@
+import * as std from '@jkcfg/std';
+import { render } from '@jkcfg/std/render';
+
+render('echo.json', { message: 'success' }).then(r => std.log(r.message));

tests/test-plugin-echo.js.expected

@@ -0,0 +1 @@
+success