diff --git a/src/function.js b/src/function.js
index 979180b..c2e335c 100644
--- a/src/function.js
+++ b/src/function.js
@@ -1,6 +1,6 @@
 import { curry, curryN } from './curry.js'
 import { dispatch } from './fantasy-land.js'
-import { head, concat as iterconcat, iter, tail } from './list.js'
+import { head, isIterable, iterConcat, iter, tail } from './list.js'
 
 /** @import { Fn, Morphism, InferredMorphism, Predicate } from './types.js' */
 
@@ -14,7 +14,7 @@ export const id = x => x
 export const concat = dispatch(['fantasy-land/concat', 'concat'],
   (b, a) => {
     if (isIterable(a) || isIterable(b)) {
-      return iterconcat(iter(a), iter(b))
+      return iterConcat(iter(a), iter(b))
     } else {
       return a.concat(b)
     }
diff --git a/test/units/index.js b/test/units/index.js
index 47103c2..6ec5bd5 100644
--- a/test/units/index.js
+++ b/test/units/index.js
@@ -1,16 +1,62 @@
-import { it, assert } from 'folktest'
+import { it, assert, assertEq } from 'folktest'
 import { dispatch } from '../../src/fantasy-land.js'
 
-const obj = {
-  'test': a => console.log('test', a)
+const test = (re, str = '') => re instanceof RegExp ? re.test(str) : new RegExp(re).test(str)
+
+const assertErr = (f, err) => {
+  try {
+    f()
+  } catch (e) {
+    if (typeof err === 'string' || err instanceof RegExp) {
+      assert(test(err, e.message), `${err} did not match ${e.message}`)
+    } else if (typeof err === 'function') {
+      assert(e.constructor === err)
+    }
+
+    return
+  }
+
+  const expected = err ? `"${err}" ` : ""
+  assert(false, `expecting error ${expected}but function did not throw`)
 }
 
-export const Tests = [
-  it('whatever', () => {
-    const f = dispatch(['fantasy-land/test', 'test'], (f, a) => {
-      console.log(f, a)
+const wrong = msg => assert(false, msg)
+
+export const Dispatch = [
+  it('should dispatch to any listed method or fallback', () => {
+    const a1 = {
+      ['fantasy-land/test']: x => assertEq(x, 1),
+      test: () => wrong(`a1['test'] should not have been called`)
+    }
+
+    const f1 = dispatch(['fantasy-land/test', 'test'], (v, x) => {
+      wrong(`f1 fallback should not have been called for ${JSON.stringify(x)}`)
     })
-    console.log(f(1, obj))
+
+    f1(1, a1)
+
+    delete a1['fantasy-land/test']
+
+    assertErr(() => {
+      f1(1, a1)
+    })
+
+    const f2 = dispatch(['test', 'fantasy-land/test'], (v, x) => {
+      wrong(`f2 fallback should not have been called for ${JSON.stringify(x)}`)
+    })
+
+    const a2 = {
+      ['fantasy-land/test']: () => wrong(`a2['fantasy-land/test'] should not have been called`),
+      test: x => assertEq(x, 2)
+    }
+
+    f2(2, a2)
+
+    const f3 = dispatch(['fantasy-land/test', 'test'], x => {
+      assertEq(x, 3)
+    })
+
+    f3(3, {})
   })
 ]