diff --git a/lib-arrow/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt b/lib-arrow/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt
index ab2754c..ed7d897 100644
--- a/lib-arrow/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt
+++ b/lib-arrow/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt
@@ -36,7 +36,7 @@ class TransitionerTest : StringSpec({
   }
 
   "effects valid transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner()
 
     transitioner.transition(Letter(A), transition) shouldBeRight Letter(B)
@@ -47,7 +47,7 @@ class TransitionerTest : StringSpec({
   }
 
   "ignores completed transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner()
 
     transitioner.transition(Letter(B), transition) shouldBeRight Letter(B)
@@ -58,7 +58,7 @@ class TransitionerTest : StringSpec({
   }
 
   "returns error on invalid transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner()
 
     transitioner.transition(Letter(C), transition).shouldBeLeft()
@@ -72,7 +72,7 @@ class TransitionerTest : StringSpec({
   "returns error when preHook errors" {
     val error = RuntimeException("preHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(pre = { _, _ -> error.left() })
 
     transitioner.transition(Letter(A), transition) shouldBeLeft error
@@ -99,7 +99,7 @@ class TransitionerTest : StringSpec({
   "returns error when postHook errors" {
     val error = RuntimeException("postHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(post = { _, _, _ -> error.left() })
 
     transitioner.transition(Letter(A), transition) shouldBeLeft error
@@ -112,7 +112,7 @@ class TransitionerTest : StringSpec({
   "returns error when preHook throws" {
     val error = RuntimeException("preHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(pre = { _, _ -> throw error })
 
     transitioner.transition(Letter(A), transition) shouldBeLeft error
@@ -138,7 +138,7 @@ class TransitionerTest : StringSpec({
   "returns error when postHook throws" {
     val error = RuntimeException("postHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(post = { _, _, _ -> throw error })
 
     transitioner.transition(Letter(A), transition) shouldBeLeft error
@@ -150,7 +150,7 @@ class TransitionerTest : StringSpec({
   "returns error when persist fails" {
     val error = RuntimeException("persist error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(persist = { error.left() })
 
     transitioner.transition(Letter(A), transition) shouldBeLeft error
@@ -163,7 +163,7 @@ class TransitionerTest : StringSpec({
   "returns error when persist throws" {
     val error = RuntimeException("persist error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(persist = { throw error })
 
     transitioner.transition(Letter(A), transition) shouldBeLeft error
@@ -259,7 +259,7 @@ class TransitionerTest : StringSpec({
   }
 
   "pre hook contains the correct from value and transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(
       pre = { value, t ->
         value shouldBe Letter(A)
@@ -275,7 +275,7 @@ class TransitionerTest : StringSpec({
   "post hook contains the correct from state, post value and transition" {
     val transition = transition(from = B, to = C)
     val transitioner = transitioner(
-      post = { from, value, t->
+      post = { from, value, t ->
         from shouldBe B
         value shouldBe Letter(C)
         t shouldBe transition
diff --git a/lib/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt b/lib/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt
index 80abce1..e993c6e 100644
--- a/lib/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt
+++ b/lib/src/test/kotlin/app/cash/kfsm/TransitionerTest.kt
@@ -32,7 +32,7 @@ class TransitionerTest : StringSpec({
   }
 
   "effects valid transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner()
 
     transitioner.transition(Letter(A), transition) shouldBeSuccess Letter(B)
@@ -43,7 +43,7 @@ class TransitionerTest : StringSpec({
   }
 
   "ignores completed transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner()
 
     transitioner.transition(Letter(B), transition) shouldBeSuccess Letter(B)
@@ -54,7 +54,7 @@ class TransitionerTest : StringSpec({
   }
 
   "returns error on invalid transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner()
 
     transitioner.transition(Letter(C), transition).shouldBeFailure()
@@ -68,7 +68,7 @@ class TransitionerTest : StringSpec({
   "returns error when preHook errors" {
     val error = RuntimeException("preHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(pre = { _, _ -> Result.failure(error) })
 
     transitioner.transition(Letter(A), transition) shouldBeFailure error
@@ -95,7 +95,7 @@ class TransitionerTest : StringSpec({
   "returns error when postHook errors" {
     val error = RuntimeException("postHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(post = { _, _, _ -> Result.failure(error) })
 
     transitioner.transition(Letter(A), transition) shouldBeFailure error
@@ -108,7 +108,7 @@ class TransitionerTest : StringSpec({
   "returns error when preHook throws" {
     val error = RuntimeException("preHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(pre = { _, _ -> throw error })
 
     transitioner.transition(Letter(A), transition) shouldBeFailure error
@@ -134,7 +134,7 @@ class TransitionerTest : StringSpec({
   "returns error when postHook throws" {
     val error = RuntimeException("postHook error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(post = { _, _, _ -> throw error })
 
     transitioner.transition(Letter(A), transition) shouldBeFailure error
@@ -146,7 +146,7 @@ class TransitionerTest : StringSpec({
   "returns error when persist fails" {
     val error = RuntimeException("persist error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(persist = { Result.failure(error) })
 
     transitioner.transition(Letter(A), transition) shouldBeFailure error
@@ -159,7 +159,7 @@ class TransitionerTest : StringSpec({
   "returns error when persist throws" {
     val error = RuntimeException("persist error")
 
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(persist = { throw error })
 
     transitioner.transition(Letter(A), transition) shouldBeFailure error
@@ -255,7 +255,7 @@ class TransitionerTest : StringSpec({
   }
 
   "pre hook contains the correct from value and transition" {
-    val transition = transition()
+    val transition = transition(from = A, to = B)
     val transitioner = transitioner(
       pre = { value, t ->
         value shouldBe Letter(A)
@@ -271,7 +271,7 @@ class TransitionerTest : StringSpec({
   "post hook contains the correct from state, post value and transition" {
     val transition = transition(from = B, to = C)
     val transitioner = transitioner(
-      post = { from, value, t->
+      post = { from, value, t ->
         from shouldBe B
         value shouldBe Letter(C)
         t shouldBe transition