Explore creating robust HTTP services in Scala's functional programming paradigm. Gain insights into pure vs. impure implementations, their pros and cons, and effective tool usage.

scala-platform.tar.gz

Scala-Pure

Scala-Impure

Scala-Tapir

Scala-Impure-Test

Scala-Pure-Test

Scala-Tapir-Test

Test

Scala - Run Code Widget 

Scala-Pure-copy

Scala is one of the most popular general-purpose languages that supports both object-oriented and functional programming. In this course, you will learn how to create back-end HTTP services using Scala's functional programming paradigm.

You will also learn how to develop, test, and document the service using both pure and impure ways. You will be exposed to the differences between pure and impure implementation, their respective pros and cons, and how pure implementation can be more robust in terms of performance, understandability, testability, and type safeness. 

By the end of the course, you will have a clear idea of how functional programming works in Scala and how you can use the available tools more effectively.

Pure Functional HTTP APIs in Scala

# Load a non-existing product 


Let’s write a test for our first use case: loading a product! 

Again, we will use the `beforeEach` and `afterEach` helpers to clean up our database. Let’s take a look at a test for loading a product that does not exist.

"Loading a Product by ID" when {
  "the ID does not exist" must {
    val expectedStatus = StatusCodes.NotFound
    
    s"return $expectedStatus" in {
      val id = UUID.randomUUID
      
      for {
        resp <- http.singleRequest(
          HttpRequest(
            method = HttpMethods.GET,
            uri = s"$baseUrl/product/$id",
            headers = Seq(),
            entity = HttpEntity(
              contentType = ContentTypes.`application/json`,
              data = ByteString("")
            )
          )
        )
      } yield {
        resp.status must be(expectedStatus)
      }
    }
  }
}

Maybe a bit verbose, but we make a real HTTP request, and check the response status code. 

If we were to run it, the output would look something like this:

Learn how to test the endpoints for loading existing and non-existing products.

Introduction

Impure Implementation

Pure Implementation

Testing Impure Services

Testing Pure Services

Benchmarks

Documentation

Epilogue

Testing the Routes: Use Case - Loading

Load a non-existing product