diffx does its best to show the difference in the most readable way, but obviously the default configuration won’t cover all the use-cases. Because of that, there are few ways how you can modify its output.

intellij idea

If you are running tests using IntelliJ IDEA’s test runner, you will want to turn off the red text coloring it uses for test failure outputs because it interferes with difflicious’ color outputs.

In File | Settings | Editor | Color Scheme | Console Colors | Console | Error Output, uncheck the red foreground color. (Solution provided by Jacob Wang @jatcwang)

colors & signs

Diffx refers to the values that are compared as left and right, but you can think of them as actual and expected.

By default, the difference is shown in the following form:

leftColor(leftValue) -> rightColor(rightValue)

When comparing collection types the difference is calculated against the right value

rightColor(additionalValue) when there is an additional entity on the left-hand side leftColor(missingValue) when there is a missing entity on the left-hand side

Where, by default, rightColor is green and leftColor is red.

Colors can be customized providing an implicit instance of ConsoleColorConfig class. In fact rightColor and leftColor are functions string => string so they can be modified to do whatever you want with the output. One example of that would be to use some special characters instead of colors, which might be useful on some environments like e.g. CI.

val colorConfigWithPlusMinus: ConsoleColorConfig =
    ConsoleColorConfig(default = identity, arrow = identity, right = s => "+" + s, left = s => "-" + s)

There are two predefined set of colors - light and dark theme. The default theme is dark, and it can be changed using environment variable - DIFFX_COLOR_THEME(light/dark).

skipping identical

In some cases it might be desired to skip rendering the identical fields, to do that simple set showIgnored to false.

case class Person(name:String, age:Int)

val result = compare(Person("Bob", 23), Person("Alice", 23))
// result: DiffResult = DiffResultObject(
//   name = "Person",
//   fields = ListMap(
//     "name" -> DiffResultString(
//       diffs = List(
//         DiffResultStringLine(
//           diffs = List(DiffResultValue(left = "Bob", right = "Alice"))
//         )
//       )
//     ),
//     "age" -> IdenticalValue(value = 23)
//   )
// )
result.show(renderIdentical = false)
// res1: String = """Person(
//      name: Bob -> Alice)"""