diff --git a/solve-classic/src/commonTest/kotlin/it/unibo/tuprolog/solve/systemtest/TestClassicNotUnify.kt b/solve-classic/src/commonTest/kotlin/it/unibo/tuprolog/solve/systemtest/TestClassicNotUnify.kt
index f928e33d3..714ede7d5 100644
--- a/solve-classic/src/commonTest/kotlin/it/unibo/tuprolog/solve/systemtest/TestClassicNotUnify.kt
+++ b/solve-classic/src/commonTest/kotlin/it/unibo/tuprolog/solve/systemtest/TestClassicNotUnify.kt
@@ -10,39 +10,10 @@ import it.unibo.tuprolog.solve.stdlib.DefaultBuiltins
 import it.unibo.tuprolog.theory.Theory
 import kotlin.test.Test
 
-class TestClassicNotUnify : TestNotUnify, SolverFactory {
+class TestClassicNotUnify : TestNotUnify, SolverFactory by ClassicSolverFactory {
 
     private val prototype = TestNotUnify.prototype(this)
 
-    override val defaultBuiltins: AliasedLibrary
-        get() = DefaultBuiltins
-
-    override fun solverOf(
-            libraries: Libraries,
-            flags: FlagStore,
-            staticKb: Theory,
-            dynamicKb: Theory,
-            stdIn: InputChannel<String>,
-            stdOut: OutputChannel<String>,
-            stdErr: OutputChannel<String>,
-            warnings: OutputChannel<PrologWarning>
-    ) = Solver.classic(
-            libraries, flags, staticKb, dynamicKb, stdIn, stdOut, stdErr, warnings
-    )
-
-    override fun mutableSolverOf(
-            libraries: Libraries,
-            flags: FlagStore,
-            staticKb: Theory,
-            dynamicKb: Theory,
-            stdIn: InputChannel<String>,
-            stdOut: OutputChannel<String>,
-            stdErr: OutputChannel<String>,
-            warnings: OutputChannel<PrologWarning>
-    ) = MutableSolver.classic(
-            libraries, flags, staticKb, dynamicKb, stdIn, stdOut, stdErr, warnings
-    )
-
     @Test
     override fun testNumberNotUnify() {
         prototype.testNumberNotUnify()
diff --git a/test-solve/src/commonMain/kotlin/it/unibo/tuprolog/solve/TestNotUnify.kt b/test-solve/src/commonMain/kotlin/it/unibo/tuprolog/solve/TestNotUnify.kt
index b37c0f135..4af291c14 100644
--- a/test-solve/src/commonMain/kotlin/it/unibo/tuprolog/solve/TestNotUnify.kt
+++ b/test-solve/src/commonMain/kotlin/it/unibo/tuprolog/solve/TestNotUnify.kt
@@ -1,23 +1,11 @@
 package it.unibo.tuprolog.solve
 
-interface TestNotUnify {
-    companion object{
+interface TestNotUnify : SolverTest {
+    companion object {
         fun prototype(solverFactory: SolverFactory): TestNotUnify =
-                TestNotUnifyImpl(solverFactory)
+            TestNotUnifyImpl(solverFactory)
     }
 
-    /** A short test max duration */
-    val shortDuration: TimeDuration
-        get() = 250L
-
-    /** A medium test max duration */
-    val mediumDuration: TimeDuration
-        get() = 2 * shortDuration
-
-    /** A long test max duration */
-    val longDuration: TimeDuration
-        get() = 4 * mediumDuration
-
     /**
      * Tests the query
      * ```prolog