Ensure sibling-independent seeds

Fixes #466.
FWDekker · Sep 20, 2023 · 317fff4 · 317fff4
1 parent 799563e
commit 317fff4
Show file tree

Hide file tree

Showing 2 changed files with 52 additions and 2 deletions.
diff --git a/src/main/kotlin/com/fwdekker/randomness/template/Template.kt b/src/main/kotlin/com/fwdekker/randomness/template/Template.kt
@@ -15,6 +15,7 @@ import com.fwdekker.randomness.uuid.UuidScheme
 import com.fwdekker.randomness.word.WordScheme
 import com.intellij.ui.Gray
 import com.intellij.util.xmlb.annotations.XCollection
+import kotlin.random.Random
 
 
 /**
@@ -76,9 +77,13 @@ data class Template(
      * The schemes are first all given a reference to the same [random] before each generating [count] random strings.
      * These results are then concatenated into the output.
      */
-    override fun generateUndecoratedStrings(count: Int) =
-        schemes.onEach { it.random = random }.map { it.generateStrings(count) }
+    override fun generateUndecoratedStrings(count: Int): List<String> {
+        val seed = random.nextInt()
+
+        return schemes.onEach { it.random = Random(seed + it.uuid.hashCode()) }
+            .map { it.generateStrings(count) }
             .let { data -> (0 until count).map { i -> data.joinToString("") { it[i] } } }
+    }
 
 
     override fun doValidate() =

diff --git a/src/test/kotlin/com/fwdekker/randomness/template/TemplateTest.kt b/src/test/kotlin/com/fwdekker/randomness/template/TemplateTest.kt
@@ -1,20 +1,25 @@
 package com.fwdekker.randomness.template
 
+import com.fwdekker.randomness.CapitalizationMode
 import com.fwdekker.randomness.DataGenerationException
 import com.fwdekker.randomness.Settings
 import com.fwdekker.randomness.array.ArrayDecorator
 import com.fwdekker.randomness.integer.IntegerScheme
 import com.fwdekker.randomness.stateDeepCopyTestFactory
+import com.fwdekker.randomness.string.StringScheme
 import com.fwdekker.randomness.testhelpers.DummyScheme
 import com.fwdekker.randomness.testhelpers.shouldValidateAsBundle
+import com.fwdekker.randomness.word.WordScheme
 import io.kotest.assertions.throwables.shouldThrow
 import io.kotest.core.NamedTag
 import io.kotest.core.spec.style.FunSpec
 import io.kotest.data.row
 import io.kotest.datatest.withData
+import io.kotest.matchers.collections.shouldContainExactly
 import io.kotest.matchers.ints.shouldBeGreaterThan
 import io.kotest.matchers.shouldBe
 import io.kotest.matchers.types.shouldBeSameInstanceAs
+import kotlin.random.Random
 
 
 /**
@@ -99,6 +104,46 @@ object TemplateTest : FunSpec({
 
             shouldThrow<DataGenerationException> { template.generateStrings() }
         }
+
+        context("rng") {
+            test("returns the same given the same seed") {
+                val template = Template(schemes = mutableListOf(StringScheme("[a-zA-Z]{10}"), IntegerScheme()))
+
+                val outputs1 = template.also { it.random = Random(1) }.generateStrings(5)
+                val outputs2 = template.also { it.random = Random(1) }.generateStrings(5)
+
+                outputs1 shouldContainExactly outputs2
+            }
+
+            test("sets the rng of a scheme independent of scheme order") {
+                val schemeA = IntegerScheme()
+                val glue = StringScheme("-")
+                val schemeB = IntegerScheme()
+
+                val output1 = Template(schemes = mutableListOf(schemeA, glue, schemeB))
+                    .also { it.random = Random(1) }
+                    .generateStrings()[0]
+                val output2 = Template(schemes = mutableListOf(schemeB, glue, schemeA))
+                    .also { it.random = Random(1) }
+                    .generateStrings()[0]
+
+                output1.split("-").reversed() shouldContainExactly output2.split("-")
+            }
+
+            test("sets the rng independent of the rng of other schemes") {
+                val prefix = WordScheme(words = listOf("pre"))
+                val scheme = IntegerScheme()
+                val postfix = WordScheme(words = listOf("post"))
+                val template = Template(schemes = mutableListOf(prefix, scheme, postfix))
+
+                val output1 = template.also { it.random = Random(1) }.generateStrings()[0]
+                prefix.capitalization = CapitalizationMode.RANDOM
+                postfix.capitalization = CapitalizationMode.RANDOM
+                val output2 = template.also { it.random = Random(1) }.generateStrings()[0]
+
+                output1.drop(3).dropLast(4) shouldBe output2.drop(3).dropLast(4)
+            }
+        }
     }
 
     context("doValidate") {