1 files changed, 78 insertions, 0 deletions
diff --git a/core/src/jvmTest/kotlin/coffee/liz/rookery/ScrambleTrackerTest.kt b/core/src/jvmTest/kotlin/coffee/liz/rookery/ScrambleTrackerTest.kt
new file mode 100644
index 0000000..896aaa4
--- /dev/null
+++ b/core/src/jvmTest/kotlin/coffee/liz/rookery/ScrambleTrackerTest.kt
@@ -0,0 +1,78 @@
+package coffee.liz.rookery
+
+import coffee.liz.rookery.puzzle.Cube3x3
+import coffee.liz.rookery.puzzle.NxnCube
+import coffee.liz.rookery.puzzle.ScrambleTracker
+import coffee.liz.rookery.scramble.TnoodleScrambler
+import kotlin.test.Test
+import kotlin.test.assertEquals
+import kotlin.test.assertFalse
+import kotlin.test.assertTrue
+
+class ScrambleTrackerTest {
+    private val solver = TnoodleScrambler()
+    private fun tracker() = ScrambleTracker(solver::solve3x3)
+    private val scramble = "R U2 F' L D B2 R' U L2 F"
+
+    @Test fun followingTheScrambleWalksThePlanDown() {
+        val t = tracker()
+        t.reset(scramble, Cube3x3.SOLVED)
+        assertEquals(scramble.split(" "), t.plan)
+        t.move("R"); assertEquals("U2", t.plan[0])
+        assertEquals(scramble.split(" "), t.sequence); assertEquals(setOf(0), t.done); assertEquals(1, t.current)
+        t.move("U"); assertEquals("U", t.plan[0])          // half of a double turn
+        assertEquals(1, t.current)                          // still on the same move of the sequence
+        t.move("U"); assertEquals("F'", t.plan[0])
+        t.move("F"); assertEquals("F2", t.plan[0])          // wrong way round: two more fixes it, no solver needed
+        assertFalse(t.corrected)
+        t.move("F2")
+        for (m in listOf("L", "D", "B2", "R'", "U", "L2", "F")) t.move(m)
+        assertTrue(t.scrambled)
+        assertEquals(scramble.split(" "), t.sequence); assertEquals(t.sequence.indices.toSet(), t.done)
+    }
+
+    @Test fun oppositeFacesCanBeDoneInEitherOrder() {
+        val t = tracker()
+        t.reset("R L U", Cube3x3.SOLVED)
+        t.move("L"); assertEquals(listOf("R", "U"), t.plan)
+        assertFalse(t.corrected)
+    }
+
+    @Test fun strayMoveGetsAShortFixThatStaysPutAndReachesTheScramble() {
+        val t = tracker()
+        t.reset(scramble, Cube3x3.SOLVED)
+        t.move("R"); t.move("U2"); t.move("D")              // D is not next
+        assertTrue(t.corrected)
+        val fix = t.plan
+        assertTrue(fix.size <= 21, "fix is ${fix.size} moves")
+        // following the fix: the rest of the plan is exactly its tail each time (cached, not re-solved)
+        val cube = NxnCube(3).apply("R U2 D")
+        for ((i, m) in fix.withIndex()) { t.move(m); cube.apply(m); assertEquals(fix.drop(i + 1), t.plan) }
+        assertTrue(t.scrambled)
+        assertEquals(Cube3x3.facelets(NxnCube(3).apply(scramble)), Cube3x3.facelets(cube))
+    }
+
+    @Test fun startsFromWhateverStateTheCubeIsIn() {
+        val t = tracker()
+        t.reset(scramble, Cube3x3.facelets(NxnCube(3).apply("F R U")))
+        assertTrue(t.known && t.corrected)
+        val cube = NxnCube(3).apply("F R U")
+        for (m in t.plan.toList()) { t.move(m); cube.apply(m) }
+        assertTrue(t.scrambled)
+        assertEquals(Cube3x3.facelets(NxnCube(3).apply(scramble)), Cube3x3.facelets(cube))
+        // then solving it is noticed
+        for (m in solver.solve3x3(Cube3x3.facelets(cube))!!.split(" ")) t.move(m)
+        assertTrue(t.solved)
+    }
+
+    @Test fun wideMovesBecomeFaceTurnsReachingTheSameCubeUpToHowItIsHeld() {
+        val bld = "R U F2 Rw Uw'"
+        val faces = Cube3x3.faceTurns(bld)
+        assertEquals(listOf("R", "U", "F2", "L"), faces.take(4))
+        // same cube: rotating the wide-move result back onto its centres gives the face-turn result
+        val wide = NxnCube(3).apply(bld)
+        val plain = Cube3x3.facelets(NxnCube(3).apply(faces.joinToString(" ")))
+        val rotations = listOf("", "x", "x2", "x'", "z", "z'").flatMap { a -> listOf("", "y", "y2", "y'").map { "$a $it".trim() } }
+        assertTrue(rotations.any { Cube3x3.facelets(wide.copy().apply(it)) == plain })
+    }
+}