Add ETL exercise

config.json

@@ -217,6 +217,14 @@
         "practices": [],
         "prerequisites": [],
         "difficulty": 8
+      },
+      {
+        "slug": "etl",
+        "name": "ETL",
+        "uuid": "63792af3-0fce-4c90-8cc3-4844ad6b6861",
+        "practices": [],
+        "prerequisites": [],
+        "difficulty": 5
       }
     ]
   },

exercises/practice/etl/.docs/instructions.md

@@ -0,0 +1,27 @@
+# Instructions
+
+Your task is to change the data format of letters and their point values in the game.
+
+Currently, letters are stored in groups based on their score, in a one-to-many mapping.
+
+- 1 point: "A", "E", "I", "O", "U", "L", "N", "R", "S", "T",
+- 2 points: "D", "G",
+- 3 points: "B", "C", "M", "P",
+- 4 points: "F", "H", "V", "W", "Y",
+- 5 points: "K",
+- 8 points: "J", "X",
+- 10 points: "Q", "Z",
+
+This needs to be changed to store each individual letter with its score in a one-to-one mapping.
+
+- "a" is worth 1 point.
+- "b" is worth 3 points.
+- "c" is worth 3 points.
+- "d" is worth 2 points.
+- etc.
+
+As part of this change, the team has also decided to change the letters to be lower-case rather than upper-case.
+
+~~~~exercism/note
+If you want to look at how the data was previously structured and how it needs to change, take a look at the examples in the test suite.
+~~~~

exercises/practice/etl/.docs/introduction.md

@@ -0,0 +1,16 @@
+# Introduction
+
+You work for a company that makes an online multiplayer game called Lexiconia.
+
+To play the game, each player is given 13 letters, which they must rearrange to create words.
+Different letters have different point values, since it's easier to create words with some letters than others.
+
+The game was originally launched in English, but it is very popular, and now the company wants to expand to other languages as well.
+
+Different languages need to support different point values for letters.
+The point values are determined by how often letters are used, compared to other letters in that language.
+
+For example, the letter 'C' is quite common in English, and is only worth 3 points.
+But in Norwegian it's a very rare letter, and is worth 10 points.
+
+To make it easier to add new languages, your team needs to change the way letters and their point values are stored in the game.

exercises/practice/etl/.meta/config.json

@@ -0,0 +1,22 @@
+{
+  "authors": [
+    "Steffan153"
+  ],
+  "files": {
+    "solution": [
+      "etl.sql"
+    ],
+    "test": [
+      "etl_test.sql"
+    ],
+    "example": [
+      ".meta/example.sql"
+    ],
+    "editor": [
+      "data.csv"
+    ]
+  },
+  "blurb": "Change the data format for scoring a game to more easily add other languages.",
+  "source": "Based on an exercise by the JumpstartLab team for students at The Turing School of Software and Design.",
+  "source_url": "https://turing.edu"
+}

exercises/practice/etl/.meta/example.sql

@@ -0,0 +1,10 @@
+UPDATE etl
+SET result = (
+    SELECT json_group_object(LOWER(value), TRIM(path, '$."') + 0)
+    FROM (
+        SELECT value, path
+        FROM json_tree(input)
+        WHERE type = 'text'
+        ORDER BY value
+    )
+);

exercises/practice/etl/.meta/tests.toml

@@ -0,0 +1,22 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[78a7a9f9-4490-4a47-8ee9-5a38bb47d28f]
+description = "single letter"
+
+[60dbd000-451d-44c7-bdbb-97c73ac1f497]
+description = "single score with multiple letters"
+
+[f5c5de0c-301f-4fdd-a0e5-df97d4214f54]
+description = "multiple scores with multiple letters"
+
+[5db8ea89-ecb4-4dcd-902f-2b418cc87b9d]
+description = "multiple scores with differing numbers of letters"

exercises/practice/etl/canonical-data.json

@@ -0,0 +1,105 @@
+{
+  "exercise": "etl",
+  "comments": [
+    "Transforms a set of legacy Lexiconia data stored as letters per score",
+    "to a set of data stored score per letter.",
+    "Note:  The expected input data for these tests should have",
+    "integer keys (not stringified numbers as shown in the JSON below",
+    "Unless the language prohibits that, please implement these tests",
+    "such that keys are integers. e.g. in JavaScript, it might look ",
+    "like `transform( { 1: ['A'] } );`"
+  ],
+  "cases": [
+    {
+      "uuid": "78a7a9f9-4490-4a47-8ee9-5a38bb47d28f",
+      "description": "single letter",
+      "property": "transform",
+      "input": {
+        "legacy": {
+          "1": ["A"]
+        }
+      },
+      "expected": {
+        "a": 1
+      }
+    },
+    {
+      "uuid": "60dbd000-451d-44c7-bdbb-97c73ac1f497",
+      "description": "single score with multiple letters",
+      "property": "transform",
+      "input": {
+        "legacy": {
+          "1": ["A", "E", "I", "O", "U"]
+        }
+      },
+      "expected": {
+        "a": 1,
+        "e": 1,
+        "i": 1,
+        "o": 1,
+        "u": 1
+      }
+    },
+    {
+      "uuid": "f5c5de0c-301f-4fdd-a0e5-df97d4214f54",
+      "description": "multiple scores with multiple letters",
+      "property": "transform",
+      "input": {
+        "legacy": {
+          "1": ["A", "E"],
+          "2": ["D", "G"]
+        }
+      },
+      "expected": {
+        "a": 1,
+        "d": 2,
+        "e": 1,
+        "g": 2
+      }
+    },
+    {
+      "uuid": "5db8ea89-ecb4-4dcd-902f-2b418cc87b9d",
+      "description": "multiple scores with differing numbers of letters",
+      "property": "transform",
+      "input": {
+        "legacy": {
+          "1": ["A", "E", "I", "O", "U", "L", "N", "R", "S", "T"],
+          "2": ["D", "G"],
+          "3": ["B", "C", "M", "P"],
+          "4": ["F", "H", "V", "W", "Y"],
+          "5": ["K"],
+          "8": ["J", "X"],
+          "10": ["Q", "Z"]
+        }
+      },
+      "expected": {
+        "a": 1,
+        "b": 3,
+        "c": 3,
+        "d": 2,
+        "e": 1,
+        "f": 4,
+        "g": 2,
+        "h": 4,
+        "i": 1,
+        "j": 8,
+        "k": 5,
+        "l": 1,
+        "m": 3,
+        "n": 1,
+        "o": 1,
+        "p": 3,
+        "q": 10,
+        "r": 1,
+        "s": 1,
+        "t": 1,
+        "u": 1,
+        "v": 4,
+        "w": 4,
+        "x": 8,
+        "y": 4,
+        "z": 10
+      }
+    }
+  ]
+}

exercises/practice/etl/create_fixture.sql

@@ -0,0 +1,8 @@
+DROP TABLE IF EXISTS "etl";
+CREATE TABLE "etl" (
+    "input" TEXT,
+    "result" TEXT
+);
+
+.mode csv
+.import ./data.csv etl

exercises/practice/etl/data.csv

@@ -0,0 +1,4 @@
+"{""1"":[""A""]}",""
+"{""1"":[""A"",""E"",""I"",""O"",""U""]}",""
+"{""1"":[""A"",""E""],""2"":[""D"",""G""]}",""
+"{""1"":[""A"",""E"",""I"",""O"",""U"",""L"",""N"",""R"",""S"",""T""],""2"":[""D"",""G""],""3"":[""B"",""C"",""M"",""P""],""4"":[""F"",""H"",""V"",""W"",""Y""],""5"":[""K""],""8"":[""J"",""X""],""10"":[""Q"",""Z""]}",""

exercises/practice/etl/etl.sql

@@ -0,0 +1,2 @@
+-- Schema: CREATE TABLE "etl" ("input" TEXT, "result" TEXT);
+-- Task: update the etl table and set the result based on the input field.

exercises/practice/etl/etl_test.sql

@@ -0,0 +1,29 @@
+-- Setup test table and read in student solution:
+.read ./test_setup.sql
+
+-- Test cases:
+INSERT INTO tests (name, uuid,
+                    input, expected)
+    VALUES
+        ('single letter', '78a7a9f9-4490-4a47-8ee9-5a38bb47d28f',
+            '{"1":["A"]}',
+            '{"a":1}'),
+        ('single score with multiple letters', '60dbd000-451d-44c7-bdbb-97c73ac1f497',
+            '{"1":["A","E","I","O","U"]}',
+            '{"a":1,"e":1,"i":1,"o":1,"u":1}'),
+        ('multiple scores with multiple letters', 'f5c5de0c-301f-4fdd-a0e5-df97d4214f54',
+            '{"1":["A","E"],"2":["D","G"]}',
+            '{"a":1,"d":2,"e":1,"g":2}'),
+        ('multiple scores with differing numbers of letters', '5db8ea89-ecb4-4dcd-902f-2b418cc87b9d',
+            '{"1":["A","E","I","O","U","L","N","R","S","T"],"2":["D","G"],"3":["B","C","M","P"],"4":["F","H","V","W","Y"],"5":["K"],"8":["J","X"],"10":["Q","Z"]}',
+            '{"a":1,"b":3,"c":3,"d":2,"e":1,"f":4,"g":2,"h":4,"i":1,"j":8,"k":5,"l":1,"m":3,"n":1,"o":1,"p":3,"q":10,"r":1,"s":1,"t":1,"u":1,"v":4,"w":4,"x":8,"y":4,"z":10}');
+
+
+-- Comparison of user input and the tests updates the status for each test:
+UPDATE tests
+SET status = 'pass'
+FROM (SELECT input, result FROM "etl") AS actual
+WHERE (actual.input, json(actual.result)) = (tests.input, json(tests.expected));
+
+-- Write results and debug info:
+.read ./test_reporter.sql

exercises/practice/etl/test_reporter.sql

@@ -0,0 +1,16 @@
+-- Update message for failed tests to give helpful information:
+UPDATE tests
+SET message = 'Result for ' || actual.input || ' is: ' || actual.result || ', but should be: ' || tests.expected
+FROM (SELECT input, result FROM etl) AS actual
+WHERE actual.input = tests.input AND tests.status = 'fail';
+
+-- Save results to ./output.json (needed by the online test-runner)
+.mode json
+.once './output.json'
+SELECT name, status, message, output, test_code, task_id
+FROM tests;
+
+-- Display test results in readable form for the student:
+.mode table
+SELECT name, status, message
+FROM tests;

exercises/practice/etl/test_setup.sql

@@ -0,0 +1,25 @@
+-- Create database:
+.read ./create_fixture.sql
+
+-- Read user student solution and save any output as markdown in user_output.md:
+.mode markdown
+.output user_output.md
+.read ./etl.sql
+.output
+
+-- Create a clean testing environment:
+DROP TABLE IF EXISTS tests;
+CREATE TABLE IF NOT EXISTS tests (
+    -- uuid and name (description) are taken from the test.toml file
+    uuid TEXT PRIMARY KEY,
+	name TEXT NOT NULL,
+    -- The following section is needed by the online test-runner
+    status TEXT DEFAULT 'fail',
+    message TEXT,
+    output TEXT,
+    test_code TEXT,
+    task_id INTEGER DEFAULT NULL,
+    -- Here are columns for the actual tests
+    input TEXT NOT NULL,
+    expected TEXT NOT NULL
+);