fix locking and race in test mocks

internal/terraform/provider_mock.go

@@ -511,6 +511,9 @@ func (p *MockProvider) ReadDataSource(r providers.ReadDataSourceRequest) (resp p
 }
 
 func (p *MockProvider) Close() error {
+	p.Lock()
+	defer p.Unlock()
+
 	p.CloseCalled = true
 	return p.CloseError
 }

internal/terraform/terraform_test.go

@@ -193,9 +193,10 @@ func testProviderFuncFixed(rp providers.Interface) providers.Factory {
 }
 
 func testProvisionerFuncFixed(rp *MockProvisioner) provisioners.Factory {
+	// make sure this provisioner has has not been closed
+	rp.CloseCalled = false
+
 	return func() (provisioners.Interface, error) {
-		// make sure this provisioner has has not been closed
-		rp.CloseCalled = false
 		return rp, nil
 	}
 }