Added setenv task

Author: Michel Casabianca

neon/task/setenv.go

@@ -0,0 +1,39 @@
+package task
+
+import (
+	"os"
+	"reflect"
+
+	"github.com/c4s4/neon/neon/build"
+)
+
+func init() {
+	build.AddTask(build.TaskDesc{
+		Name: "setenv",
+		Func: setenv,
+		Args: reflect.TypeOf(setenvArgs{}),
+		Help: `Set environment variable with given value.
+
+Arguments:
+
+- setenv: environment variable name (string).
+- value: value of this environment variable (string).
+
+Examples:
+
+    # set environment variable VERSION to value "1.2.3"
+    - setenv: 'VERSION'
+      value:  '1.2.3'`,
+	})
+}
+
+type setenvArgs struct {
+	Setenv string
+	Value  string
+}
+
+func setenv(context *build.Context, args interface{}) error {
+	params := args.(setenvArgs)
+	os.Setenv(params.Setenv, params.Value)
+	return nil
+}

test/task/setenv.yml

@@ -0,0 +1,20 @@
+doc: Built file to test tasks
+default: task_setenv
+
+properties:
+  BUILD_DIR: '../../build'
+
+targets:
+
+  task_setenv:
+    doc: Test task setenv
+    steps:
+    - setenv: 'TEST'
+      value:  'FOO'
+    - |
+      os = import("os")
+      if os.Getenv("TEST") != "FOO" {
+        throw("Setenv test failure")
+      } else {
+        println("Setenv test success")
+      }