Merge pull request #24 from zverok/lazy-enumerator-compatibility

Lazy enumerators compatibility

lib/tty/progressbar.rb

@@ -155,7 +155,10 @@ def advance(progress = 1, tokens = {})
     end
 
     # Iterate over collection either yielding computation to block
-    # or provided Enumerator.
+    # or provided Enumerator. If the bar's `total` was not set,
+    # it would be taken from `collection.count`, otherwise previously
+    # set `total` would be used. This allows using the progressbar
+    # with infinite, lazy, or slowly-calculated enumerators.
     #
     # @example
     #   bar.iterate(30.times) { ... }
@@ -170,7 +173,7 @@ def advance(progress = 1, tokens = {})
     #
     # @api public
     def iterate(collection, progress = 1, &block)
-      update(total: collection.count)
+      update(total: collection.count) unless total
       prog = Enumerator.new do |iter|
         collection.each do |elem|
           advance(progress)

spec/unit/iterate_spec.rb

@@ -43,4 +43,17 @@
 
     expect(values).to eq([0,1,2,3,4])
   end
+
+  it "does not uses collection's count if total is provided" do
+    bar = TTY::ProgressBar.new("[:bar]", output: output, total: 5)
+    iterable = 5.times
+    expect(iterable).not_to receive(:count)
+    progress = bar.iterate(iterable)
+
+    values = []
+
+    progress.each { |v| values << v }
+
+    expect(values).to eq([0,1,2,3,4])
+  end
 end