Merge pull request #147 from prometheus/sinjo-consistent-metric-stores

Test that stores return floats and fix DirectFileStore to do so

lib/prometheus/client/data_stores/direct_file_store.rb

@@ -133,7 +133,8 @@ def all_values
             end
 
             # Aggregate all the different values for each label_set
-            stores_data.each_with_object({}) do |(label_set, values), acc|
+            aggregate_hash = Hash.new { |hash, key| hash[key] = 0.0 }
+            stores_data.each_with_object(aggregate_hash) do |(label_set, values), acc|
               acc[label_set] = aggregate_values(values)
             end
           end

spec/examples/data_store_example.rb

@@ -1,13 +1,25 @@
 # encoding: UTF-8
 
+# NOTE: Do not change instances of `eql` to `eq` in this file.
+#
+# The interface of a store is a labelset (hash of hashes) to a double. It's important
+# that we check the values are doubles rather than integers. `==`, which is what `eq`
+# calls allows conversion between floats and integers (i.e. `5 == 5.0`). `eql` enforces
+# that the two numbers are of the same type.
 shared_examples_for Prometheus::Client::DataStores do
+  describe "MetricStore#set and #get" do
+    it "returns the value set for each labelset" do
+      expect(metric_store.get(labels: { foo: "bar" })).to eql(0.0)
+    end
+  end
+
   describe "MetricStore#set and #get" do
     it "returns the value set for each labelset" do
       metric_store.set(labels: { foo: "bar" }, val: 5)
       metric_store.set(labels: { foo: "baz" }, val: 2)
-      expect(metric_store.get(labels: { foo: "bar" })).to eq(5)
-      expect(metric_store.get(labels: { foo: "baz" })).to eq(2)
-      expect(metric_store.get(labels: { foo: "bat" })).to eq(0)
+      expect(metric_store.get(labels: { foo: "bar" })).to eql(5.0)
+      expect(metric_store.get(labels: { foo: "baz" })).to eql(2.0)
+      expect(metric_store.get(labels: { foo: "bat" })).to eql(0.0)
     end
   end
 
@@ -20,9 +32,9 @@
       metric_store.increment(labels: { foo: "baz" }, by: 7)
       metric_store.increment(labels: { foo: "zzz" }, by: 3)
 
-      expect(metric_store.get(labels: { foo: "bar" })).to eq(6)
-      expect(metric_store.get(labels: { foo: "baz" })).to eq(9)
-      expect(metric_store.get(labels: { foo: "zzz" })).to eq(3)
+      expect(metric_store.get(labels: { foo: "bar" })).to eql(6.0)
+      expect(metric_store.get(labels: { foo: "baz" })).to eql(9.0)
+      expect(metric_store.get(labels: { foo: "zzz" })).to eql(3.0)
     end
   end
 
@@ -49,10 +61,16 @@
       metric_store.set(labels: { foo: "bar" }, val: 5)
       metric_store.set(labels: { foo: "baz" }, val: 2)
 
-      expect(metric_store.all_values).to eq(
+      expect(metric_store.all_values).to eql(
         { foo: "bar" } => 5.0,
         { foo: "baz" } => 2.0,
       )
     end
+
+    context "for a combination of labels that hasn't had a value set" do
+      it "returns 0.0" do
+        expect(metric_store.all_values[{ foo: "bar" }]).to eql(0.0)
+      end
+    end
   end
 end