Add JSON formatter

spec/ameba/formatter/json_formatter_spec.cr

@@ -0,0 +1,78 @@
+require "../../spec_helper"
+
+module Ameba
+  def get_result(sources = [Source.new ""])
+    file = IO::Memory.new
+    formatter = Formatter::JSONFormatter.new file
+
+    formatter.started sources
+    sources.each { |source| formatter.source_finished source }
+    formatter.finished sources
+
+    JSON.parse file.to_s
+  end
+
+  describe Formatter::JSONFormatter do
+    context "metadata" do
+      it "shows ameba version" do
+        get_result["metadata"]["ameba_version"].should eq Ameba::VERSION
+      end
+
+      it "shows crystal version" do
+        get_result["metadata"]["crystal_version"].should eq Crystal::VERSION
+      end
+    end
+
+    context "sources" do
+      it "shows path to the source" do
+        result = get_result [Source.new "", "source.cr"]
+        result["sources"].first["path"].should eq "source.cr"
+      end
+
+      it "shows rule name" do
+        s = Source.new ""
+        s.error DummyRule.new, 1, 2, "message1"
+
+        result = get_result [s]
+        result["sources"].first["errors"].first["rule_name"].should eq DummyRule.name
+      end
+
+      it "shows a message" do
+        s = Source.new ""
+        s.error DummyRule.new, 1, 2, "message"
+
+        result = get_result [s]
+        result["sources"].first["errors"].first["message"].should eq "message"
+      end
+
+      it "shows error location" do
+        s = Source.new ""
+        s.error DummyRule.new, 1, 2, "message"
+
+        result = get_result [s]
+        location = result["sources"].first["errors"].first["location"]
+        location["line"].should eq 1
+        location["column"].should eq 2
+      end
+    end
+
+    context "summary" do
+      it "shows a target sources count" do
+        result = get_result [Source.new(""), Source.new("")]
+        result["summary"]["target_sources_count"].should eq 2
+      end
+
+      it "shows errors count" do
+        s1 = Source.new ""
+        s1.error DummyRule.new, 1, 2, "message1"
+        s1.error DummyRule.new, 1, 2, "message2"
+
+        s2 = Source.new ""
+        s2.error DummyRule.new, 1, 2, "message3"
+
+        result = get_result [s1, s2]
+        result["summary"]["errors_count"].should eq 3
+      end
+    end
+  end
+end