Merge pull request #222 from codecrafters-io/add-transactions-docs

Add support for INCR command and update course definition

course-definition.yml

@@ -3163,16 +3163,37 @@ stages:
     name: "The INCR command (1/3)"
     difficulty: easy
     description_md: |
-      In this stage, you'll add support for handling the `INCR` command when a key exists with numerical value.
+      In this stage, you'll add support for the `INCR` command.
 
-      **🚧 We're still working on instructions for this stage**. You can find notes on how the tester works below.
+      ### The INCR command
+
+      The [INCR](https://redis.io/docs/latest/commands/incr/) command is used to increment the value of a key by 1.
+
+      Example usage:
+
+      ```bash
+      $ redis-cli SET foo 5
+      "OK"
+      $ redis-cli INCR foo
+      (integer) 6
+      $ redis-cli INCR foo
+      (integer) 7
+      ```
+
+      If the key doesn't exist, the value will be set to 1.
+
+      We'll split the implementation of this command into three stages:
+
+      - Key exists and has a numerical value (**This stage**)
+      - Key doesn't exist (later stages)
+      - Key exists but doesn't have a numerical value (later stages)
 
       ### Tests
 
       The tester will execute your program like this:
 
-      ```
-      ./spawn_redis_server.sh
+      ```bash
+      $ ./spawn_redis_server.sh
       ```
 
       The tester will then connect to your server as a Redis client and run the following commands:
@@ -3192,14 +3213,29 @@ stages:
     description_md: |
       In this stage, you'll add support for handling the `INCR` command when a key does not exist.
 
-      **🚧 We're still working on instructions for this stage**. You can find notes on how the tester works below.
+      ### Recap
+
+      The implementation of [`INCR`](https://redis.io/docs/latest/commands/incr/) is split into three stages:
+
+      - Key exists and has a numerical value (previous stages)
+      - Key doesn't exist (**This stage**)
+      - Key exists but doesn't have a numerical value (later stages)
+
+      When a key doesn't exit, `INCR` sets the value to 1. Example:
+
+      ```bash
+      $ redis-cli INCR missing_key
+      (integer) 1
+      $ redis-cli GET missing_key
+      "1"
+      ```
 
       ### Tests
 
       The tester will execute your program like this:
 
-      ```
-      ./spawn_redis_server.sh
+      ```bash
+      $ ./spawn_redis_server.sh
       ```
 
       The tester will then connect to your server as a Redis client and run the following commands:
@@ -3209,6 +3245,10 @@ stages:
       > INCR foo (expecting ":1\r\n" as the response)
       > INCR bar (expecting ":1\r\n" as the response)
       ```
+
+      ### Notes
+
+      - Your implementation still needs to pass the tests in the previous stage.
     marketing_md: |
       In this stage, you'll continue implementing the INCR command.
 
@@ -3219,14 +3259,29 @@ stages:
     description_md: |
       In this stage, you'll add support for handling the `INCR` command when a key exists but doesn't have a numerical value.
 
-      **🚧 We're still working on instructions for this stage**. You can find notes on how the tester works below.
+      ### Recap
+
+      The implementation of [`INCR`](https://redis.io/docs/latest/commands/incr/) is split into three stages:
+
+      - Key exists and has a numerical value (previous stages)
+      - Key doesn't exist (previous stages)
+      - Key exists but doesn't have a numerical value (**This stage**)
+
+      When a key exists but doesn't have a numerical value, `INCR` will return an error. Example:
+
+      ```bash
+      $ redis-cli SET foo xyz
+      "OK"
+      $ redis-cli INCR foo
+      -ERR value is not an integer or out of range
+      ```
 
       ### Tests
 
       The tester will execute your program like this:
 
-      ```
-      ./spawn_redis_server.sh
+      ```bash
+      $ ./spawn_redis_server.sh
       ```
 
       The tester will then connect to your server as a Redis client and run the following commands: