Add local_census_records importation model

This model without database allow us to validate incoming file extension and
headers and also does the following during importation process:

* Ignore empty rows
* Classifiy rows in two groups: created_records, invalid_records

spec/models/local_census_records/import_spec.rb

@@ -0,0 +1,88 @@
+require "rails_helper"
+
+describe LocalCensusRecords::Import do
+
+  let(:base_files_path) { %w[spec fixtures files local_census_records import] }
+  let(:import) { build(:local_census_records_import) }
+
+  describe "Validations" do
+    it "is valid" do
+      expect(import).to be_valid
+    end
+
+    it "is not valid without a file to import" do
+      import.file = nil
+
+      expect(import).not_to be_valid
+    end
+
+    context "When file extension" do
+      it "is wrong it should not be valid" do
+        file = Rack::Test::UploadedFile.new("spec/fixtures/files/clippy.gif")
+        import = build(:local_census_records_import, file: file)
+
+        expect(import).not_to be_valid
+      end
+
+      it "is csv it should be valid" do
+        path = base_files_path << "valid.csv"
+        file = Rack::Test::UploadedFile.new(Rails.root.join(*path))
+        import = build(:local_census_records_import, file: file)
+
+        expect(import).to be_valid
+      end
+    end
+
+    context "When file headers" do
+      it "are all missing it should not be valid" do
+        path = base_files_path << "valid-without-headers.csv"
+        file = Rack::Test::UploadedFile.new(Rails.root.join(*path))
+        import = build(:local_census_records_import, file: file)
+
+        expect(import).not_to be_valid
+      end
+    end
+  end
+
+  context "#save" do
+    it "Create valid local census records with provided values" do
+      import.save
+      local_census_record = LocalCensusRecord.find_by(document_number: "X11556678")
+
+      expect(local_census_record).not_to be_nil
+      expect(local_census_record.document_type).to eq("NIE")
+      expect(local_census_record.document_number).to eq("X11556678")
+      expect(local_census_record.date_of_birth).to eq(Date.parse("07/08/1987"))
+      expect(local_census_record.postal_code).to eq("7008")
+    end
+
+    it "Add successfully created local census records to created_records array" do
+      import.save
+
+      valid_document_numbers = ["44556678T", "33556678T", "22556678T", "X11556678"]
+      expect(import.created_records.collect(&:document_number)).to eq(valid_document_numbers)
+    end
+
+    it "Add invalid local census records to invalid_records array" do
+      path = base_files_path << "invalid.csv"
+      file = Rack::Test::UploadedFile.new(Rails.root.join(*path))
+      import.file = file
+
+      import.save
+
+      invalid_records_document_types = [nil, "DNI", "Passport", "NIE"]
+      invalid_records_document_numbers = ["44556678T", nil, "22556678T", "X11556678"]
+      invalid_records_date_of_births = [Date.parse("07/08/1984"), Date.parse("07/08/1985"), nil,
+        Date.parse("07/08/1987")]
+      invalid_records_postal_codes = ["7008", "7009", "7010", nil]
+      expect(import.invalid_records.collect(&:document_type))
+        .to eq(invalid_records_document_types)
+      expect(import.invalid_records.collect(&:document_number))
+        .to eq(invalid_records_document_numbers)
+      expect(import.invalid_records.collect(&:date_of_birth))
+        .to eq(invalid_records_date_of_births)
+      expect(import.invalid_records.collect(&:postal_code))
+      .to eq(invalid_records_postal_codes)
+    end
+  end
+end