Add ability to specify width for multi bar

lib/tty/progressbar/multi.rb

@@ -18,6 +18,8 @@ class Multi
 
       def_delegators :@bars, :each, :empty?, :length, :[]
 
+      def_delegators :@top_bar, :width, :width=
+
       DEFAULT_INSET = {
         top:    Gem.win_platform? ? '+ '   : "\u250c ",
         middle: Gem.win_platform? ? '|-- ' : "\u251c\u2500\u2500 ",
@@ -51,6 +53,9 @@ def initialize(*args)
         @top_bar = nil
         @top_bar = register(format, observable: false) if format
 
+        @width = @options[:width]
+        @top_bar.update(width: @width) if @width
+
         @callbacks = {
           progress: [],
           stopped:  [],
@@ -73,7 +78,8 @@ def register(format, options = {})
           @bars << bar
           observe(bar) if observable
           if @top_bar
-            @top_bar.update(total: total, width: total)
+            @top_bar.update(total: total)
+            @top_bar.update(width: total) unless @width
           end
         end
 

spec/unit/multi/width_spec.rb

@@ -6,7 +6,7 @@
   let(:middle) { TTY::ProgressBar::Multi::DEFAULT_INSET[:middle] }
   let(:bottom) { TTY::ProgressBar::Multi::DEFAULT_INSET[:bottom] }
 
-  it "sets top level bar width to maximum columns when exceeds" do
+  it "sets top level bar width to maximum columns when exceeds terminal width" do
     allow(TTY::Screen).to receive(:width).and_return(15)
 
     bars = TTY::ProgressBar::Multi.new("[:bar] main", output: output)
@@ -94,4 +94,25 @@
       restore
     ].join)
   end
+
+  it "sets top level bar width to a custom value" do
+    bars = TTY::ProgressBar::Multi.new("[:bar] main", output: output, width: 20)
+
+    bar1 = bars.register("[:bar] one", total: 20)
+    bar2 = bars.register("[:bar] two", total: 20)
+
+    bar1.advance(10)
+    bar2.advance(10)
+
+    output.rewind
+    expect(output.read).to eq([
+      "\e[1G#{top}[=====               ] main\n",
+      "\e[1G#{bottom}[==========          ] one\n",
+      save,
+      "\e[2A",   # up 2 lines
+      "\e[1G#{top}[==========          ] main",
+      restore,
+      "\e[1G#{bottom}[==========          ] two\n"
+    ].join)
+  end
 end