Add test coverage on line buffer util

test/unit/vagrant/util/line_buffer_test.rb

@@ -0,0 +1,60 @@
+require File.expand_path("../../../base", __FILE__)
+require "vagrant/util/line_buffer"
+
+describe Vagrant::Util::LineBuffer do
+  it "should raise error when no callback is provided" do
+    expect { subject }.to raise_error(ArgumentError)
+  end
+
+  context "with block defined" do
+    let(:block) { proc{ |l| output << l } }
+    let(:output) { [] }
+    let(:partial) { "this is part of a line. " }
+    let(:line) { "this is a full line\n" }
+
+    subject { described_class.new(&block) }
+
+    it "should not raise an error when callback is provided" do
+      expect { subject }.not_to raise_error
+    end
+
+    describe "#<<" do
+      it "should add line to the output" do
+        subject << line
+        expect(output).to eq([line.rstrip])
+      end
+
+      it "should not add partial line to output" do
+        subject << partial
+        expect(output).to be_empty
+      end
+
+      it "should add partial line to output once full line is given" do
+        subject << partial
+        expect(output).to be_empty
+        subject << line
+        expect(output).to eq([partial + line.rstrip])
+      end
+
+      it "should add line once it has surpassed max line length" do
+        overflow = "a" * (described_class.const_get(:MAX_LINE_LENGTH) + 1)
+        subject << overflow
+        expect(output).to eq([overflow])
+      end
+    end
+
+    describe "#close" do
+      it "should output any partial data left in buffer" do
+        subject << partial
+        expect(output).to be_empty
+        subject.close
+        expect(output).to eq([partial])
+      end
+
+      it "should not be writable after closing" do
+        subject.close
+        expect { subject << partial }.to raise_error(FrozenError)
+      end
+    end
+  end
+end