Rules_Engine_Example

Overview

This project includes an implementation of a simple rule engine that determines whether a person qualifies for a given product and sets an interest rate for the person based on predefined rules. The rulebase is designed to be easily updated, with rules defined and implemented separately from the code that executes them.

Contents

The rules are declared as rows in a csv file with the columns defined as follows:

• 1: rule index (unique identifier)
• 2: rule condition input (value of property that triggers rule)
• 3: rule action (adjustment made to a specific property when rule fires)
• 4: rule description (text description of rule)

All classes are defined in RulesEngine.py, while rules are declared as rows in Rule_definitions.txt, which can be easily updated without updating the rule execution code. Several tests have been included in the RulesEngine.py file to handle expected uses and incorrect inputs.

Instructions

The code is written in Python (Python 3) and can be run fron the command line using the command python RulesEngine.py.

Problem Statement

You have been tasked by a stakeholder to develop a solution that allows the business to dynamically generating product pricing from a set rules defined by the finance team. The finance team has given you an initial set of rules on how to price the products, however, these rules could change at any time so we need to be able to update the rules easily and rerun the product pricing to see the new prices of the products.

Initial Rules:

• All products start at 5.0 interest_rate.
• If the person lives in Florida (condition), we do not offer the product to them and the product is to be disqualified (action).
• If the person has a credit score greater than or equal to 720(condition) then we reduce the interest_rate on the product by .3 (action that has an input of “.3”, remember the business may decide in the future they want to reduce it by .5).
• If the person has a credit score lower than 720 we increase the interest_rate on the product by .5.
• If the name of the product is “7-1 ARM” then we need to add .5 to the interest_rate of the product.

Example:

class Person:   
  credit_score: integer   
  state: string     
 
class Product:   
  name:  string   
  interest_rate: decimal   
  disqualified: boolean     
  
class RulesEngine   
  def runRules(person, product, rules)     
    person = new Person(720, ‘Florida’)     
    product = new Product(‘7-1 ARM’, 5.0) 
  
rules_engine = new RulesEngine() 
 
rules = loadRules() // Rules are loaded at runtime!     

rules_engine.runRules(person, product, rules**); 

**Hint: We have not defined how the rules are represented, they could be json, csv, etc. The only thing that matters is that rule definitions can be extended upon and defined outside of the code, the rule definitions should define an action, any parameters an action needs, and under what condition to execute the action.

The output of the above code example should be:

product.interest_rate == 5.2 ( 5.0 - .3 + .5 ) 
 
product.disqualified == true  

Expectations:

1. Build a rules engine to accomplish what the business has asked above.

2. Exhaustively test all possible rule outcomes and assert that the rules engine works as expected and meets the business requirements.

3. Show the extendibility of your rules engine and create your own rule definition to execute an additional action on a product.