Add mocking module

index.js

@@ -1,4 +1,5 @@
 export * from './reporter/index.js'
+export * from './lib/mock.js'
 export { suite } from './lib/suite.js'
 
 import { metaltest } from './lib/metaltest.js'

lib/mock.js

@@ -0,0 +1,56 @@
+
+const capture = (actions, name, fn) => async (...args) => {
+  const count = actions.reduce((count, curr) => {
+    if (curr.name === name) return count + 1
+
+    return count
+  }, 1)
+
+  try {
+    const result = await fn(...args, { count })
+    actions.push({ name, args, result })
+    return result
+  } catch (error) {
+    actions.push({ name, args, result: error })
+    throw error
+  }
+}
+
+const mock = async (mocks, fn) => {
+  const olds = {}
+  const actions = []
+
+  for (const mock of mocks) {
+    if (mock.package in olds === false) olds[mock.package] = {}
+    const old = olds[mock.package]
+
+    for (const name in mock.funcs) {
+      //Save
+      old[name] = mock.package[name]
+
+      //Capture
+      mock.package[name] = capture(actions, name, mock.funcs[name])
+    }
+  }
+
+  //Restore even when an error occurs
+  //Like with a failed assert
+  try {
+    await fn()
+  } catch (error) {
+    throw error
+  } finally {
+    for (const mock of mocks) {
+      const old = olds[mock.package]
+
+      for (const name in mock.funcs) {
+        //Restore
+        mock.package[name] = old[name]
+      }
+    }
+  }
+
+  return actions
+}
+
+export { mock }