Merge pull request #8495 from chrisroberts/fix/ssh-comm-empty-data

communicator/ssh: Do not pass empty data to registered blocks

plugins/communicators/ssh/communicator.rb

@@ -519,7 +519,7 @@ module VagrantPlugins
                   end
                 end
 
-                if block_given? && marker_found
+                if block_given? && marker_found && !data.empty?
                   yield :stdout, data
                 end
               end
@@ -540,7 +540,7 @@ module VagrantPlugins
                 end
               end
 
-              if block_given? && marker_found
+              if block_given? && marker_found && !data.empty?
                 yield :stderr, data
               end
             end

test/unit/plugins/communicators/ssh/communicator_test.rb

@@ -168,6 +168,24 @@ describe VagrantPlugins::CommunicatorSSH::Communicator do
       end
     end
 
+    context "with no command output" do
+      let(:command_stdout_data) do
+        "#{command_garbage_marker}"
+      end
+
+      it "does not send empty stdout data string" do
+        empty = true
+        expect(
+          communicator.execute("ls /") do |type, data|
+            if type == :stdout && data.empty?
+              empty = false
+            end
+          end
+        ).to eq(0)
+        expect(empty).to be(true)
+      end
+    end
+
     context "with garbage content prepended to command stderr output" do
       let(:command_stderr_data) do
         "Line of garbage\nMore garbage\n#{command_garbage_marker}bin\ntmp\n"
@@ -186,6 +204,24 @@ describe VagrantPlugins::CommunicatorSSH::Communicator do
       end
     end
 
+    context "with no command output on stderr" do
+      let(:command_stderr_data) do
+        "#{command_garbage_marker}"
+      end
+
+      it "does not send empty stderr data string" do
+        empty = true
+        expect(
+          communicator.execute("ls /") do |type, data|
+            if type == :stderr && data.empty?
+              empty = false
+            end
+          end
+        ).to eq(0)
+        expect(empty).to be(true)
+      end
+    end
+
     context "with pty enabled" do
       before do
         expect(ssh).to receive(:pty).and_return true