Add some private projects

soundcloud/solution/.gitignore

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+.python-version
+__pycache__
+*.pyc

soundcloud/solution/README.md

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+## SoundCloud backend engineering code review interview exercise
+
+### Introduction
+
+Welcome to the SoundCloud backend Pull Request review challenge!
+
+This repository contains a simulation of a microservice. The service is
+intentionally simplistic. The code for the service is python, but only using
+basic aspects of the language. 
+We intend this to read like pseudocode - and in particular 
+_we do not judge your submission based on your knowledge of Python_. Exposure to 
+any popular programming language(s) should be enough to effectively work this exercise.
+
+You will be reviewing Pull Request #1 (present under the "Pull Requests" tab).
+It's meant to be a simplified simulation of the sort of code review you might
+encounter in your everyday work.
+
+> Also see: [a quick introduction to GitHub pull requests](https://help.github.com/en/articles/about-pull-request-reviews#about-pull-request-reviews).
+
+## Your challenge
+
+The code should be robust and reasonably feature-complete.
+We only want to merge this Pull Request once you and your (imaginary) colleague are confident that:
+
+  - The implementation actually supports the requested feature.
+  - The implementation is likely to work, including proper handling of
+    easily-foreseeable corner cases.
+  - The implementation is not easy for a mailcious user to attack.
+  - Other engineers can productively and confidently change this code, meaning:
+    - The code is clear and straightforward to reason through.
+    - It has high-quality unit tests and good test coverage.
+    - It's well-organized and code elements have intention-revealing names.
+    - There are comments, where those are useful.
+
+In short, we are interested in gaining some insight into what is important to
+you when you review code. We'll be concentrating especially on what you feel
+is important to change, and the way you communicate that. Please provide change
+requests, ask questions, and otherwise make comments as you normally would when
+reviewing code.
+
+The only GitHub review features that matter in this exercise are
+commenting-related: commenting on the whole Pull Request, and comments targeted at specific
+areas of the code. If you prefer to make use of Github's markdown features
+in your comments, please feel free to do so - but if you haven't used these features
+before, please do not use them.
+
+As a general guideline, this exercise should take about 30-60 minutes. You are free
+to take more (or less) time than that, however.
+
+When you're done, please notify your SoundCloud recruiter contact via email.

soundcloud/solution/src/clients/product_detail_client.py

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+"""
+Interview note:
+    This is a client "stub", here for demonstration and documentation
+    purposes only.
+
+    In a real production environment, this client would send requests over
+    the network to a product detail backend service.
+
+The product detail backend service is responsible for retrieving product
+detail records from its datastore (e.g., a mysql database), and
+returning them to callers.
+"""
+class ProductDetailClient:
+
+    def lookup(product_token):
+        """
+        Given a product token, makes a blocking call to the lookup endpoint of
+        the product detail backend service,
+        and returns a corresponding product detail record, if found.
+        If no record is found, returns None.
+
+        Example result:
+
+        {"token": "AAA",
+         "description": "Red Bike",
+         "price_cents": 45000}
+        """
+        pass
+
+    def batch_lookup(product_tokens):
+        """
+        Given a list of product tokens, makes a blocking call to the
+        batch lookup endpoint of the product detail backend service,
+        and returns a map of product token to product detail record, for all
+        that are found.
+        Any records that cannot be found are ommitted from the result.
+
+        Example result:
+
+        {"AAA": {
+            "token": "AAA",
+            "description": "Red Bike",
+            "price_cents": 45000},
+         "BBB": {
+            "token": "BBB",
+            "description": "Blue Bike",
+            "price_cents": 37500}}
+        """
+        pass

soundcloud/solution/src/clients/product_search_client.py

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+"""
+Interview note:
+    This is a client "stub", here for demonstration and documentation
+    purposes only.
+
+    In a real production environment, this client would send requests over
+    the network to a product search backend service.
+
+The product search backend service is responsible for performing lookups
+against a product search index (e.g., elasticsearch) and returning product
+tokens that are search result "hits".
+"""
+class ProductSearchClient:
+
+    def search_for_all_in_price_range(lower_cents, upper_cents, start_record, num_records):
+        """
+        Given a price range plus pagination information,
+        returns a list of product tokens of products
+        whose price falls in the range.
+
+        The price range is inclusive - that is,
+        a given price "p" matches if:
+
+        upper_cents >= p >= lower_cents
+
+        If no products have prices in the price range,
+        returns an empty list.
+
+        Product tokens are ordered by price, from lowest to highest.
+
+        Out of the total list of possible product tokens,
+        only the "page" of product tokens starting at the list position
+        start_record, and ending at start_record+num_records, are returned.
+
+        If start_record+num_records is greater than the number of actual
+        result records, the resulting list size will be (accordingly)
+        smaller than num_records.
+
+        Example result:
+
+        ["AAA",
+         "BBB"]
+        """
+        pass

soundcloud/solution/src/service.py

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+import re
+
+TOKEN_REGEX = re.compile("^[0-9A-F-]+$")
+
+class Service:
+    def __init__(self, product_detail_client, product_search_client):
+        self.product_detail_client = product_detail_client
+        self.product_search_client = product_search_client
+
+    def lookup(self, product_token):
+        """
+        Given a valid product token,
+        lookup product detail information from the product detail backend service.
+
+        - Results in Bad Request if the token is invalid
+        - Results in Not Found if the product is unknown to the backend service
+        """
+        if not TOKEN_REGEX.match(product_token):
+            return {"status": 400}
+
+        lookup_result = self.product_detail_client.lookup(product_token)
+        if lookup_result:
+            return {"status": 200, "product": lookup_result}
+        else:
+            return {"status": 404}
+
+    def search_by_price_range(self, lower_cents, upper_cents, start_record, num_records):
+        page_of_product_tokens = \
+            self.product_search_client.search_for_all_in_price_range(
+                lower_cents,
+                upper_cents,
+                start_record,
+                num_records)
+
+        product_detail_results = []
+        for product_token in page_of_product_tokens:
+            product_detail_results.append(self.lookup(product_token)["product"])
+
+        return {"status": 200, "products": product_detail_results}
+
+if __name__ == "__main__":
+    a = Service()
+    print(a.lookup('aaa'))

soundcloud/solution/test/service_test.py

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+import os
+import sys
+import unittest
+
+sys.path.append(os.path.join(os.path.dirname(os.path.realpath(__file__)), "../src"))
+
+from service import Service
+
+
+class ProductDetailClientTestDouble:
+    def __init__(self):
+        self.contents = {}
+
+    def lookup(self, product_token):
+        if product_token in self.contents:
+            return self.contents[product_token]
+        else:
+            return None
+
+class ProductSearchClientTestDouble:
+    def __init__(self):
+        self.search_to_results = {}
+
+    def search_for_all_in_price_range(self, lower_cents, upper_cents, start_record, num_records):
+        return self.search_to_results[(lower_cents, upper_cents, start_record, num_records)]
+
+class ServiceTest(unittest.TestCase):
+    def setUp(self):
+        self.detail_client = ProductDetailClientTestDouble()
+        self.search_client = ProductSearchClientTestDouble()
+        self.service = Service(self.detail_client, self.search_client)
+
+    def test_lookup_success(self):
+        expected_product = {
+            "token": "AAA",
+            "description": "Red Bike",
+            "price_cents": 45000
+        }
+
+        self.detail_client.contents["AAA"] = expected_product
+
+        self.assertEqual(
+            self.service.lookup("AAA"),
+            {"status": 200,
+             "product": expected_product})
+
+    def test_lookup_not_found(self):
+        self.assertEqual(
+            self.service.lookup("AAA"),
+            {"status": 404})
+
+    def test_lookup_bad_input(self):
+        self.assertEqual(
+            self.service.lookup("this-is-not-a-uuid"),
+            {"status": 400})
+
+    def test_search_price_range(self):
+        brown_bike = {
+            "token": "AAA",
+            "description": "Brown Bike",
+            "price_cents": 10000
+        }
+
+        blue_bike = {
+            "token": "BBB",
+            "description": "Blue Bike",
+            "price_cents": 37500
+        }
+
+        red_bike = {
+            "token": "CCC",
+             "description": "Red Bike",
+             "price_cents": 45000
+        }
+
+        gray_bike = {
+            "token": "DDD",
+             "description": "Gray Bike",
+             "price_cents": 99900
+        }
+
+        self.detail_client.contents["AAA"] = brown_bike
+        self.detail_client.contents["BBB"] = blue_bike
+        self.detail_client.contents["CCC"] = red_bike
+        self.detail_client.contents["DDD"] = gray_bike
+
+        self.search_client.search_to_results[(30000, 50000, 0, 10)] = ["BBB", "CCC"]
+
+        self.assertEqual(
+            self.service.search_by_price_range(30000, 50000, 0, 10),
+            {"status": 200,
+             "products": [blue_bike, red_bike]})
+
+if __name__ == '__main__':
+    unittest.main()