Add 'docker cp' command

docker.go

@@ -29,6 +29,7 @@ type Docker struct {
 	}
 
 	Pull DockerPull
+	Copy DockerCopy
 }
 
 func NewDocker() Docker {
@@ -52,6 +53,7 @@ func NewDocker() Docker {
 	docker.Volume.Remove = DockerVolumeRemove{executable: executable}
 
 	docker.Pull = DockerPull{executable: executable}
+	docker.Copy = DockerCopy{executable: executable}
 
 	return docker
 }
@@ -71,6 +73,7 @@ func (d Docker) WithExecutable(executable Executable) Docker {
 	d.Volume.Remove.executable = executable
 
 	d.Pull.executable = executable
+	d.Copy.executable = executable
 
 	return d
 }
@@ -411,3 +414,20 @@ func (p DockerPull) Execute(image string) error {
 
 	return nil
 }
+
+type DockerCopy struct {
+	executable Executable
+}
+
+func (docker DockerCopy) Execute(source, dest string) error {
+	stderr := bytes.NewBuffer(nil)
+	err := docker.executable.Execute(pexec.Execution{
+		Args:   []string{"cp", source, dest},
+		Stderr: stderr,
+	})
+	if err != nil {
+		return fmt.Errorf("'docker cp' failed: %w: %s", err, strings.TrimSpace(stderr.String()))
+	}
+
+	return nil
+}

docker_test.go

@@ -880,4 +880,34 @@ func testDocker(t *testing.T, context spec.G, it spec.S) {
 
 		})
 	})
+
+	context("Copy", func() {
+		it("will execute 'docker cp SOURCE DEST'", func() {
+			err := docker.Copy.Execute("source/path", "dest-container:/path")
+			Expect(err).NotTo(HaveOccurred())
+
+			Expect(executable.ExecuteCall.Receives.Execution.Args).To(Equal([]string{
+				"cp",
+				"source/path",
+				"dest-container:/path",
+			}))
+		})
+
+		context("failure cases", func() {
+			context("when the cp command fails", func() {
+				it.Before(func() {
+					executable.ExecuteCall.Stub = func(execution pexec.Execution) error {
+						_, err := fmt.Fprint(execution.Stderr, "must specify at least one container source")
+						Expect(err).NotTo(HaveOccurred())
+						return errors.New("exit status 1")
+					}
+				})
+
+				it("returns an error", func() {
+					err := docker.Copy.Execute("source", "dest")
+					Expect(err).To(MatchError("'docker cp' failed: exit status 1: must specify at least one container source"))
+				})
+			})
+		})
+	})
 }