Add spec for GitHub issue 55

https://github.com/icy-arctic-fox/spectator/issues/55

spec/issues/github_issue_55_spec.cr

@@ -0,0 +1,48 @@
+require "../spec_helper"
+
+Spectator.describe "GitHub Issue #55" do
+  GROUP_NAME = "CallCenter"
+
+  let(name) { "TimeTravel" }
+  let(source) { "my.time.travel.experiment" }
+
+  class Analytics(T)
+    property start_time = Time.local
+    property end_time = Time.local
+
+    def initialize(@brain_talker : T)
+    end
+
+    def instrument(*, name, source, &)
+      @brain_talker.send(payload: {
+        :group  => GROUP_NAME,
+        :name   => name,
+        :source => source,
+        :start  => start_time,
+        :end    => end_time,
+      }, action: "analytics")
+    end
+  end
+
+  double(:brain_talker, send: nil)
+
+  let(brain_talker) { double(:brain_talker) }
+  let(analytics) { Analytics.new(brain_talker) }
+
+  it "tracks the time it takes to run the block" do
+    analytics.start_time = expected_start_time = Time.local
+    expected_end_time = expected_start_time + 10.seconds
+    analytics.end_time = expected_end_time + 0.5.seconds # Offset to ensure non-exact match.
+
+    analytics.instrument(name: name, source: source) do
+    end
+
+    expect(brain_talker).to have_received(:send).with(payload: {
+      :group  => GROUP_NAME,
+      :name   => name,
+      :source => source,
+      :start  => expected_start_time,
+      :end    => be_within(1.second).of(expected_end_time),
+    }, action: "analytics")
+  end
+end