Add throwOnNotFound method

lib/proxyquire.js

@@ -96,6 +96,19 @@ Proxyquire.prototype.preserveCache = function () {
   return this.fn
 }
 
+/**
+ * Stubbing a module that does not exist (from the perspective of the proxyquire
+ * subject) will throw an error.
+ * @name throwOnUnresolvedImports
+ * @function
+ * @private
+ * @return {object} The proxyquire function to allow chaining
+ */
+Proxyquire.prototype.throwOnUnresolvedImports = function () {
+  this._throwOnUnresolvedImports = true
+  return this.fn
+}
+
 /**
  * Loads a module using the given stubs instead of their normally resolved required modules.
  * @param request The requirable module path to load.
@@ -140,6 +153,10 @@ Proxyquire.prototype._resolveModule = function (baseModule, pathToResolve) {
       paths: Module.globalPaths
     })
   } catch (err) {
+    if (this._throwOnUnresolvedImports) {
+      throw new ProxyquireError('Invalid stub: "' + pathToResolve + '" is not required by the proxyquired object')
+    }
+
     // If this is not a relative path (e.g. "foo" as opposed to "./foo"), and
     // we couldn't resolve it, then we just let the path through unchanged.
     // It's safe to do this, because if two different modules require "foo",

test/proxyquire-argumentvalidation.js

@@ -63,4 +63,18 @@ describe('Illegal parameters to resolve give meaningful errors', function () {
       throws(act, /Invalid stub: "myStub" cannot be undefined/)
     })
   })
+
+  describe('when I pass a stub with a key that is not required on the proxyquired object', function () {
+    function act () {
+      const proxyquireThrowOnUnresolvedImports = proxyquire.throwOnUnresolvedImports()
+
+      proxyquireThrowOnUnresolvedImports('./samples/foo', {
+        nonExistent: () => {}
+      })
+    }
+
+    it('throws an exception with the stub key', function () {
+      throws(act, /Invalid stub: "nonExistent" is not required by the proxyquired object/)
+    })
+  })
 })