Add default labels (lang and version) to all containers started

Closes #43

Author: guilleiguaran

core/lib/testcontainers/docker_container.rb

@@ -52,7 +52,9 @@ def initialize(image, name: nil, command: nil, entrypoint: nil, exposed_ports: n
       @volumes = add_volumes(volumes) if volumes
       @env = add_env(env) if env
       @filesystem_binds = add_filesystem_binds(filesystem_binds) if filesystem_binds
-      @labels = add_labels(labels) if labels
+      @labels = {}
+      add_labels(default_labels)
+      add_labels(labels) if labels
       @working_dir = working_dir
       @healthcheck = add_healthcheck(healthcheck) if healthcheck
       @wait_for = add_wait_for(wait_for)
@@ -1005,6 +1007,13 @@ def store_file(path, contents)
 
     private
 
+    def default_labels
+      {
+        "org.testcontainers.lang" => "ruby",
+        "org.testcontainers.version" => Testcontainers::VERSION
+      }
+    end
+
     def normalize_ports(ports)
       return if ports.nil?
       return ports if ports.is_a?(Hash)

core/test/docker_container_test.rb

@@ -110,7 +110,7 @@ def test_it_creates_and_returns_the_container_volumes
 
   def test_it_returns_the_container_labels
     container = Testcontainers::DockerContainer.new("hello-world", labels: {"foo" => "bar"})
-    assert_equal({"foo" => "bar"}, container.labels)
+    assert_equal({"org.testcontainers.lang" => "ruby", "org.testcontainers.version" => "0.2.0", "foo" => "bar"}, container.labels)
   end
 
   def test_it_returns_the_container_env
@@ -182,7 +182,7 @@ def test_it_adds_a_label
     container = Testcontainers::DockerContainer.new("hello-world")
     container.add_label("foo", "bar")
 
-    assert_equal({"foo" => "bar"}, container.labels)
+    assert_equal({"org.testcontainers.lang" => "ruby", "org.testcontainers.version" => "0.2.0", "foo" => "bar"}, container.labels)
   end
 
   def test_it_adds_a_wait_for_with_default
@@ -234,7 +234,7 @@ def test_it_can_be_mutated_with_the_with_method
     assert_equal({"80/tcp" => [{"HostPort" => "8080"}], "443/tcp" => [{"HostPort" => ""}]}, container.port_bindings)
     assert_equal({"/tmp" => {}, "/root" => {}}, container.volumes)
     assert_equal(["/tmp/docker:/tmp:rw", "/home/user:/root:rw"], container.filesystem_binds)
-    assert_equal({"foo" => "bar"}, container.labels)
+    assert_equal({"org.testcontainers.lang" => "ruby", "org.testcontainers.version" => "0.2.0", "foo" => "bar"}, container.labels)
     assert_equal(["PATH=/usr/bin"], container.env)
     assert_equal("/app", container.working_dir)
     assert_kind_of(Proc, container.wait_for)