normalizes a date/timestamp to be timezone of the system it's coming from. input can be Time, DateTime, Date, or String -- we don't know what we'll get, so handle all of these.

soap_method_specs.rb

require 'rails_helper'

RSpec.describe Soap::Methods::InstanceMethods do
  describe "normalize_timestamp" do
    class Foo
      include Soap::Methods
    end

    def et value
      Foo.new({}, "").normalize_timestamp value
    end

    it "returns a given Time" do
      time = Time.new(2015, 6, 3, 16, 47, 14, '+05:00')
      expect(et time).to eq time
    end

    it "returns a given Date" do
      date = Date.today
      expect(et date).to eq date
    end

    it "interprets a date string" do
      date = Date.civil(2015, 6, 3)
      expect(et date.strftime("%Y-%m-%d")).to eq date
    end

    it "interprets 2015-06-03T16:47:14" do
      time = Time.new(2015, 6, 3, 16, 47, 14, '+05:00')
      expect(time.strftime("%H:%M:%S")).to eq "16:47:14"
      expect(et "2015-06-03T16:47:14").to eq time
      expect(et "2015-06-03 16:47:14").to eq time
    end
  end
end

soap_methods.rb

TIME_REGEXP = /(\d{4})\-(\d{2})\-(\d{2})[\s|T](\d{2})\:(\d{2})\:(\d{2})/
DATE_REGEXP = /(\d{4})\-(\d{2})\-(\d{2})/
SRC_TIME_OFFSET = "+05:00"

def normalize_timestamp ts
  return unless ts
  case 
  when ts.is_a?(DateTime)
    DateTime.new(ts.year, ts.month, ts.day, ts.hour, ts.min, ts.sec, SRC_TIME_OFFSET)
  when ts.is_a?(Time)
    Time.new(ts.year, ts.month, ts.day, ts.hour, ts.min, ts.sec, SRC_TIME_OFFSET)
  when ts.is_a?(String)
    if ts.match(TIME_REGEXP)
      return Time.new(*ts.match(TIME_REGEXP).captures.map(&:to_i), SRC_TIME_OFFSET)
    end
    if ts.match(DATE_REGEXP)
      return Date.civil *ts.match(DATE_REGEXP).captures.map(&:to_i)
    end
  else 
    return ts
  end
end