diff --git a/lib/aruba/command_monitor.rb b/lib/aruba/command_monitor.rb
index 79208398..2ac19e5a 100644
--- a/lib/aruba/command_monitor.rb
+++ b/lib/aruba/command_monitor.rb
@@ -98,7 +98,7 @@ def clear
     def all_stdout
       registered_commands.each(&:stop)
 
-      registered_commands.each_with_object("") { |e, a| a << e.stdout }
+      registered_commands.map(&:stdout).join
     end
 
     # Get stderr of all commands
@@ -108,7 +108,7 @@ def all_stdout
     def all_stderr
       registered_commands.each(&:stop)
 
-      registered_commands.each_with_object("") { |e, a| a << e.stderr }
+      registered_commands.map(&:stderr).join
     end
 
     # Get stderr and stdout of all commands
diff --git a/spec/aruba/command_monitor_spec.rb b/spec/aruba/command_monitor_spec.rb
index fc338b6c..ffd91f0d 100644
--- a/spec/aruba/command_monitor_spec.rb
+++ b/spec/aruba/command_monitor_spec.rb
@@ -5,19 +5,50 @@
 RSpec.describe Aruba::CommandMonitor do
   let(:monitor) { described_class.new(announcer: announcer) }
   let(:announcer) { instance_double(Aruba::Platforms::Announcer) }
-  let(:process) { instance_double(Aruba::Processes::BasicProcess, commandline: "foobar") }
+  let(:foo_process) do
+    instance_double(Aruba::Processes::InProcess, commandline: "foo",
+                                                 stop: nil,
+                                                 stdout: "foo_stdout\n",
+                                                 stderr: "foo_stderr\n")
+  end
+  let(:bar_process) do
+    instance_double(Aruba::Processes::InProcess, commandline: "bar",
+                                                 stop: nil,
+                                                 stdout: "bar_stdout\n",
+                                                 stderr: "bar_stderr\n")
+  end
 
   before do
-    monitor.register_command(process)
+    monitor.register_command(foo_process)
+    monitor.register_command(bar_process)
   end
 
   describe "#find" do
     it "find the process with the given name" do
-      expect(monitor.find("foobar")).to eq process
+      expect(monitor.find("foo")).to eq foo_process
     end
 
     it "fails if no process with the given name exists" do
       expect { monitor.find("boofar") }.to raise_error Aruba::CommandNotFoundError
     end
   end
+
+  describe "#all_stdout" do
+    it "combines stdout from all registered processs" do
+      expect(monitor.all_stdout).to eq "foo_stdout\nbar_stdout\n"
+    end
+  end
+
+  describe "#all_stderr" do
+    it "combines stderr from all registered processs" do
+      expect(monitor.all_stderr).to eq "foo_stderr\nbar_stderr\n"
+    end
+  end
+
+  describe "#all_output" do
+    it "combines stdout and stderr from all registered processs" do
+      expect(monitor.all_output)
+        .to eq "foo_stdout\nbar_stdout\nfoo_stderr\nbar_stderr\n"
+    end
+  end
 end