Introduce data builder class

Why:
We would like to separate the responsibilities of the builder and the
formatter such that it is easier to maintain

this commit:
introduces a builder class which will build the data hash for the
financial datum model

Introduce data_builder base class

app/models/csv_builder.rb

@@ -0,0 +1,6 @@
+class CsvBuilder < DataBuilder
+  def build(csv_row, user_id)
+    datum_as_hash = csv_row.to_h
+    formatter.format(datum_as_hash, user_id)
+  end
+end

app/models/csv_importer.rb

@@ -1,10 +1,17 @@
 require "csv"
 
 class CsvImporter < FileImporter
+  attr_reader :builder
+
+  def initialize(filename, user_id)
+    super
+    @builder = CsvBuilder.new
+  end
+
   def import
     CSV.foreach(file_path, headers: true) do |row|
-      formatted_datum = formatter.build_csv(row, user_id)
-      datum = FinancialDatum.new(formatted_datum)
+      raw_data = builder.build(row, user_id)
+      datum = FinancialDatum.new(raw_data)
       datum.save
     end
   end

app/models/data_builder.rb

@@ -0,0 +1,11 @@
+class DataBuilder
+  attr_reader :formatter
+
+  def initialize
+    @formatter = FinancialDataFormatter.new
+  end
+
+  def build
+    raise "Override this method"
+  end
+end

app/models/file_importer.rb

@@ -1,10 +1,9 @@
 class FileImporter
-  attr_reader :file_path, :user_id, :formatter
+  attr_reader :file_path, :user_id
 
   def initialize(file_path, user_id)
     @file_path = file_path
     @user_id = user_id
-    @formatter = FinancialDataFormatter.new
   end
 
   def import

app/models/financial_data_formatter.rb

@@ -1,21 +1,7 @@
 class FinancialDataFormatter
-  def build_csv(csv_row, user_id)
-    datum_as_hash = csv_row.to_h
-    format_base_hash(datum_as_hash, user_id)
-  end
-
-  def build_xlsx(xlsx_row, user_id)
-    cells = xlsx_row.cells.map(&:value)
-    headers = %w[month year income expenses net_worth]
-    datum_as_hash = headers.zip(cells).to_h
-    format_base_hash(datum_as_hash, user_id)
-  end
-
-  private
-
-  def format_base_hash(datum_as_hash, user_id)
-    datum_as_hash["user_id"] = user_id
-    datum_as_hash["month"] = FinancialDatum::MONTHS[datum_as_hash["month"].to_i]
-    datum_as_hash
+  def format(raw_data, user_id)
+    raw_data[:user_id] = user_id
+    raw_data[:month] = FinancialDatum::MONTHS[raw_data["month"].to_i]
+    raw_data.symbolize_keys!
   end
 end

app/models/xlsx_builder.rb

@@ -0,0 +1,8 @@
+class XlsxBuilder < DataBuilder
+  def build(xlsx_row, user_id)
+    cells = xlsx_row.cells.map(&:value)
+    headers = %w[month year income expenses net_worth]
+    datum_as_hash = headers.zip(cells).to_h
+    formatter.format(datum_as_hash, user_id)
+  end
+end

app/models/xlsx_importer.rb

@@ -1,13 +1,20 @@
 class XlsxImporter < FileImporter
+  attr_reader :builder
+
+  def initialize(filename, user_id)
+    super
+    @builder = XlsxBuilder.new
+  end
+
   def import
     workbook = RubyXL::Parser.parse(file_path)
     worksheet = workbook.worksheets.first
     worksheet.each_with_index do |row, idx|
       if idx == 0
         next
       end
-      formatted_datum = formatter.build_xlsx(row, user_id)
-      datum = FinancialDatum.new(formatted_datum)
+      raw_data = builder.build(row, user_id)
+      datum = FinancialDatum.new(raw_data)
       datum.save
     end
   end

spec/models/csv_builder_spec.rb

@@ -0,0 +1,31 @@
+require "rails_helper"
+require "csv"
+
+RSpec.describe CsvBuilder do
+  describe "#build" do
+    it "returns a hash of the data for a FinancialDatum" do
+      month = 1
+      year = 2019
+      expenses = 12345
+      income = 1000
+      net_worth = 999999
+      headers = %w[month year expenses income net_worth]
+      fields = [month, year, expenses, income, net_worth]
+      csv_row = CSV::Row.new(headers, fields)
+      user_id = 1
+      builder = CsvBuilder.new
+      expected_result = {
+        month: :february,
+        year: year,
+        expenses: expenses,
+        income: income,
+        net_worth: net_worth,
+        user_id: user_id,
+      }
+
+      result = builder.build(csv_row, user_id)
+
+      expect(result).to eq(expected_result)
+    end
+  end
+end

spec/models/data_builder_spec.rb

@@ -0,0 +1,12 @@
+require "rails_helper"
+require "csv"
+
+RSpec.describe DataBuilder do
+  describe "#build" do
+    it "raises if it is called" do
+      builder = DataBuilder.new
+
+      expect { builder.build }.to raise_error("Override this method")
+    end
+  end
+end

spec/models/file_importer_spec.rb

@@ -2,13 +2,14 @@
 
 RSpec.describe FileImporter do
   describe ".new" do
-    it "initializes with a file path and user_id and a formatter" do
-      filepath = "filepath"
+    it "initializes with a file path and user_id and a builder" do
+      file_path = "filepath"
       user_id = 1
 
-      importer = FileImporter.new(filepath, user_id)
+      importer = FileImporter.new(file_path, user_id)
 
-      expect(importer.formatter).to be_an_instance_of(FinancialDataFormatter)
+      expect(importer.file_path).to eq(file_path)
+      expect(importer.user_id).to eq(user_id)
     end
   end
 end

spec/models/financial_data_formatter_spec.rb

@@ -1,72 +1,25 @@
 require "rails_helper"
-require "csv"
 
 RSpec.describe FinancialDataFormatter do
-  describe "#build_csv" do
-    it "returns a hash of the data for a FinancialDatum" do
-      month = 1
-      year = 2019
-      expenses = 12345
-      income = 1000
-      net_worth = 999999
-      headers = %w[month year expenses income net_worth]
-      fields = [month, year, expenses, income, net_worth]
-      csv_row = CSV::Row.new(headers, fields)
-      user_id = 1
-      formatter = FinancialDataFormatter.new
-      expected_result = {
-        month: :february,
-        year: year,
-        expenses: expenses,
-        income: income,
-        net_worth: net_worth,
-        user_id: user_id,
+  describe "#format" do
+    it "takes a raw data hash and formats to the correct format" do
+      raw_data = {
+        month: 1, year: 2019, expenses: 10, income: 11, net_worth: 13,
       }
-        .stringify_keys
-
-      result = formatter.build_csv(csv_row, user_id)
-
-      expect(result).to eq(expected_result)
-    end
-  end
-
-  describe "#build_xlsx" do
-    it "returns a hash of the data for a FinancialDatum" do
-      month = 1
-      year = 2019
-      expenses = 12345
-      income = 1000
-      net_worth = 999999
-      cell_one = build_cell(1, 0, month)
-      cell_two = build_cell(1, 1, year)
-      cell_three = build_cell(1, 2, income)
-      cell_four = build_cell(1, 3, expenses)
-      cell_five = build_cell(1, 4, net_worth)
-      xlsx_row = RubyXL::Row.new
-      xlsx_row.cells = [cell_one, cell_two, cell_three, cell_four, cell_five]
       user_id = 1
       formatter = FinancialDataFormatter.new
       expected_result = {
-        month: :february,
-        year: year,
-        expenses: expenses,
-        income: income,
-        net_worth: net_worth,
-        user_id: user_id,
+        month: :january,
+        year: 2019,
+        expenses: 10,
+        income: 11,
+        net_worth: 13,
+        user_id: 1,
       }
-        .stringify_keys
 
-      result = formatter.build_xlsx(xlsx_row, user_id)
+      result = formatter.format(raw_data, user_id)
 
       expect(result).to eq(expected_result)
     end
   end
-
-  def build_cell(row, column, value)
-    cell = RubyXL::Cell.new
-    cell.row = row
-    cell.column = column
-    allow(cell).to receive(:value).and_return(value)
-    cell
-  end
 end

spec/models/xlsx_builder_spec.rb

@@ -0,0 +1,42 @@
+require "rails_helper"
+
+RSpec.describe XlsxBuilder do
+  describe "#build" do
+    it "returns a hash of the data for a FinancialDatum" do
+      month = 1
+      year = 2019
+      expenses = 12345
+      income = 1000
+      net_worth = 999999
+      cell_one = build_cell(1, 0, month)
+      cell_two = build_cell(1, 1, year)
+      cell_three = build_cell(1, 2, income)
+      cell_four = build_cell(1, 3, expenses)
+      cell_five = build_cell(1, 4, net_worth)
+      xlsx_row = RubyXL::Row.new
+      xlsx_row.cells = [cell_one, cell_two, cell_three, cell_four, cell_five]
+      user_id = 1
+      builder = XlsxBuilder.new
+      expected_result = {
+        month: :february,
+        year: year,
+        expenses: expenses,
+        income: income,
+        net_worth: net_worth,
+        user_id: user_id,
+      }
+
+      result = builder.build(xlsx_row, user_id)
+
+      expect(result).to eq(expected_result)
+    end
+  end
+
+  def build_cell(row, column, value)
+    cell = RubyXL::Cell.new
+    cell.row = row
+    cell.column = column
+    allow(cell).to receive(:value).and_return(value)
+    cell
+  end
+end