diff --git a/spec/data/work-dates.json b/spec/data/work-dates.json
new file mode 100644
index 0000000..0eecd84
--- /dev/null
+++ b/spec/data/work-dates.json
@@ -0,0 +1,14 @@
+[
+	{
+		"date": "2019-01-01",
+		"hours": 10
+	},
+	{
+		"date": "2019-01-02",
+		"hours": 6
+	},
+	{
+		"date": "2019-01-03",
+		"hours": 4
+	}
+]
\ No newline at end of file
diff --git a/spec/dayoff_spec.cr b/spec/dayoff_spec.cr
index 5cfe5ef..a35f282 100644
--- a/spec/dayoff_spec.cr
+++ b/spec/dayoff_spec.cr
@@ -1,9 +1,8 @@
 require "./spec_helper"
 
 describe Dayoff do
-  # TODO: Write tests
-
-  it "works" do
-    false.should eq(true)
+  it "can calc work hours" do
+    app = Dayoff::App.new("./spec/data/work-dates.json")
+    app.get_work_hours.should eq 20
   end
 end
diff --git a/src/dayoff.cr b/src/dayoff.cr
index 589b05f..8295190 100644
--- a/src/dayoff.cr
+++ b/src/dayoff.cr
@@ -1,6 +1,29 @@
-# TODO: Write documentation for `Dayoff`
+require "json"
+
 module Dayoff
   VERSION = "0.1.0"
 
-  # TODO: Put your code here
+  class WorkDate
+    JSON.mapping(
+      date: String,
+      hours: Int32,
+    )
+  end
+
+  class App
+    def initialize(wh_path)
+      content = File.open(wh_path) do |file|
+        file.gets_to_end
+      end
+      @wdates = Array(WorkDate).from_json(content)
+    end
+
+    def get_work_hours
+      sum = 0
+      @wdates.each do |wd|
+        sum += wd.hours
+      end
+      sum
+    end
+  end
 end