Allow to increment counters and measure histograms without tags

Using empty tags (`{}`) as default.

Resolves #26

CHANGELOG.md

@@ -32,6 +32,16 @@ and this project adheres to [Semantic Versioning](http://semver.org/spec/v2.0.0.
   )
   ```
 
+### Changed
+
+- Don't require to provide tags for counters and histograms, use empty tags (`{}`) by default. See discussion at [#26](https://github.com/yabeda-rb/yabeda/issues/26). [@Envek]
+
+  ```ruby
+  Yabeda.foo.increment
+  # same as
+  Yabeda.foo.increment({}, by: 1)
+  ```
+
 ### Fixed
 
 - Railtie loading to prevent calling methods that have not yet been defined

lib/yabeda/counter.rb

@@ -3,7 +3,7 @@
 module Yabeda
   # Growing-only counter
   class Counter < Metric
-    def increment(tags, by: 1)
+    def increment(tags = {}, by: 1)
       all_tags = ::Yabeda::Tags.build(tags, group)
       values[all_tags] += by
       adapters.each_value do |adapter|

lib/yabeda/gauge.rb

@@ -12,11 +12,11 @@ def set(tags, value)
       value
     end
 
-    def increment(tags, by: 1)
+    def increment(tags = {}, by: 1)
       set(tags, get(tags).to_i + by)
     end
 
-    def decrement(tags, by: 1)
+    def decrement(tags = {}, by: 1)
       set(tags, get(tags).to_i - by)
     end
   end

lib/yabeda/histogram.rb

@@ -7,7 +7,7 @@ class Histogram < Metric
     option :buckets
 
     # rubocop: disable Metrics/MethodLength
-    def measure(tags, value = nil)
+    def measure(tags = {}, value = nil)
       if value.nil? ^ block_given?
         raise ArgumentError, "You must provide either numeric value or block for Yabeda::Histogram#measure!"
       end

lib/yabeda/summary.rb

@@ -5,7 +5,7 @@ module Yabeda
   # calculate averages, percentiles, and so on.
   class Summary < Metric
     # rubocop: disable Metrics/MethodLength
-    def observe(tags, value = nil)
+    def observe(tags = {}, value = nil)
       if value.nil? ^ block_given?
         raise ArgumentError, "You must provide either numeric value or block for Yabeda::Summary#observe!"
       end

spec/yabeda/counter_spec.rb

@@ -15,11 +15,16 @@
     end
     Yabeda.configure! unless Yabeda.already_configured?
     allow(Yabeda::Tags).to receive(:build).with(tags, anything).and_return(built_tags)
+    allow(Yabeda::Tags).to receive(:build).with({}, anything).and_return({})
     Yabeda.register_adapter(:test_adapter, adapter)
   end
 
   it { expect(increment_counter).to eq(metric_value) }
 
+  it "increments counter with empty tags if tags are not provided" do
+    expect { counter.increment }.to change { counter.values[{}] }.by(1)
+  end
+
   it "execute perform_counter_increment! method of adapter" do
     increment_counter
     expect(adapter).to have_received(:perform_counter_increment!).with(counter, built_tags, metric_value)

spec/yabeda/histogram_spec.rb

@@ -16,6 +16,7 @@
     end
     Yabeda.configure! unless Yabeda.already_configured?
     allow(Yabeda::Tags).to receive(:build).with(tags, anything).and_return(built_tags)
+    allow(Yabeda::Tags).to receive(:build).with({}, anything).and_return({})
     Yabeda.register_adapter(:test_adapter, adapter)
   end
 
@@ -39,6 +40,11 @@
       measure_histogram
       expect(adapter).to have_received(:perform_histogram_measure!).with(histogram, built_tags, be_between(0.01, 0.05))
     end
+
+    it "measures with empty tags if tags are not provided", :aggregate_failures do
+      histogram.measure(&block)
+      expect(adapter).to have_received(:perform_histogram_measure!).with(histogram, {}, be_between(0.01, 0.05))
+    end
   end
 
   context "with both value and block provided" do

spec/yabeda/summary_spec.rb

@@ -14,6 +14,7 @@
     Yabeda.configure { summary :test_summary }
     Yabeda.configure! unless Yabeda.already_configured?
     allow(Yabeda::Tags).to receive(:build).with(tags, anything).and_return(built_tags)
+    allow(Yabeda::Tags).to receive(:build).with({}, anything).and_return({})
     Yabeda.register_adapter(:test_adapter, adapter)
   end
 
@@ -37,6 +38,11 @@
       observe_summary
       expect(adapter).to have_received(:perform_summary_observe!).with(summary, built_tags, be_between(0.01, 0.05))
     end
+
+    it "observes with empty tags if tags are not provided", :aggregate_failures do
+      summary.observe(&block)
+      expect(adapter).to have_received(:perform_summary_observe!).with(summary, {}, be_between(0.01, 0.05))
+    end
   end
 
   context "with both value and block provided" do