Merge pull request #39 from ReneeVandervelde/data-module

Add Transformed validator functions

data/api/data.api

@@ -400,6 +400,10 @@ public final class com/inkapplications/data/validator/PassingValidator : com/ink
 	public fun validate (Ljava/lang/Object;Lkotlin/coroutines/Continuation;)Ljava/lang/Object;
 }
 
+public final class com/inkapplications/data/validator/TransformedValidatorKt {
+	public static final fun transformedWith (Lcom/inkapplications/data/validator/DataValidator;Lcom/inkapplications/data/transformer/DataTransformer;)Lcom/inkapplications/data/validator/DataValidator;
+}
+
 public abstract class com/inkapplications/data/validator/ValidationError : java/lang/Error {
 	public fun <init> (Ljava/lang/String;Ljava/lang/Throwable;)V
 	public synthetic fun <init> (Ljava/lang/String;Ljava/lang/Throwable;ILkotlin/jvm/internal/DefaultConstructorMarker;)V

data/src/commonMain/kotlin/com/inkapplications/data/validator/TransformedValidator.kt

@@ -0,0 +1,27 @@
+package com.inkapplications.data.validator
+
+import com.inkapplications.data.transformer.DataTransformer
+
+/**
+ * Runs a validation check after first transforming the input to a different type.
+ */
+private class TransformedValidator<INPUT, VALIDATION>(
+    private val transformer: DataTransformer<INPUT, VALIDATION>,
+    private val validator: DataValidator<VALIDATION>,
+): DataValidator<INPUT> {
+    override suspend fun validate(input: INPUT): ValidationResult {
+        return validator.validate(transformer.transform(input))
+    }
+}
+
+/**
+ * Run this validator after first transforming the data.
+ *
+ * This is useful when needing to use a validator for a different type than
+ * the necessary input type.
+ */
+fun <INPUT, VALIDATION> DataValidator<VALIDATION>.transformedWith(
+    transformer: DataTransformer<INPUT, VALIDATION>
+): DataValidator<INPUT> {
+    return TransformedValidator(transformer, this)
+}

data/src/commonTest/kotlin/com/inkapplications/data/validator/TransformedValidatorTest.kt

@@ -0,0 +1,32 @@
+package com.inkapplications.data.validator
+
+import com.inkapplications.data.transformer.DataTransformer
+import kotlinx.coroutines.test.runTest
+import kotlin.test.*
+
+class TransformedValidatorTest {
+    @Test
+    fun transforms() = runTest {
+        val validationError = object: ValidationError(
+            message = "test-message",
+        ) {}
+        var validationInput: String? = null
+        val spyValidator = object: DataValidator<String> {
+            override suspend fun validate(input: String): ValidationResult {
+                validationInput = input
+                return ValidationResult.Failed(validationError)
+            }
+        }
+        val transformer = object: DataTransformer<Int, String> {
+            override fun transform(data: Int): String = "test-transformation"
+            override fun reverseTransform(data: String): Int = TODO()
+        }
+
+        val testValidator = spyValidator.transformedWith(transformer)
+        val result = testValidator.validate(5)
+
+        assertTrue(result is ValidationResult.Failed, "Result from validator is used")
+        assertSame(validationError, result.reasons.single(), "Exact result from validator is used")
+        assertEquals("test-transformation", validationInput, "Input is transformed")
+    }
+}