Check if a String matches this String interpolation

Question

I want to compare a string content with string interpolation. The string interpolation is for example

s"Hello ${name} ,
Your order ${UUID} will be shipped on ${date}."

There are some constraints that can be expressed in regular expressions.

The date is in this format 2018-03-19T16:14:46.191+01:00 ( +%Y-%m-%dT%H:%M:%S ).

The UUID is randomized and follows this format 834aa5fd-af26-416d-b715-adca01a866c4 .

One possible solution is to check if the string result contains some fixed part of the String interpolation.

Question

Constraint : you don't know in advance the parameters values in the String interpolation.

How would you check the value of a String interpolation ?

In general, how to test a String comparison with String interpolation if you don't know in advance the parameters values?

The solution can be given in Java. Scala is preferred.

Answer 1

You could define the variables in your test. For example, with the following function:

def stringToTest(name: String, UUID: String, date: String): String = {
  s"Hello ${name}, Your order ${UUID} will be shipped on ${date}."
}

You could write a test like this (assuming you're using something like FlatSpec with Matchers in your tests):

"my function" should {
  "return the correct string" in {
    val name = "Name"
    val UUID = "834aa5fd-af26-416d-b715-adca01a866c4"
    val date = "2018-03-19T16:14:46.191+01:00"

    stringToTest(name, UUID, date) shouldBe "Hello Name, Your order 834aa5fd-af26-416d-b715-adca01a866c4 will be shipped on 2018-03-19T16:14:46.191+01:00."
  }
}

You should be able to test each function independently, and able to use dummy values passed into the function without a problem. If you are using truly random values though (or want to over-complicate your tests), I guess you could use a regex check. Easiest way I've found is something like this:

"this string" should {
  "match the correct regex" in {
    val regex = "^Hello .*, " +
      "Your order .{8}-.{4}-.{4}-.{4}-.{12} will be shipped on " +
      "\d{4}-\d{2}-\d{2}T\d{2}:\d{2}:\d{2}.\d{3}\+\d{2}:\d{2}\.$" // whatever

    val thingToCheck = "Hello Name, " +
      "Your order 834aa5fd-af26-416d-b715-adca01a866c4 will be shipped on " +
      "2018-03-19T16:14:46.191+01:00."

    thingToCheck.matches(regex) shouldBe true
  }
}