github.com/GoogleCloudPlatform/compute-image-tools/cli_tools

cli_tools uses gomock. The mocks are stored as source code, and need to be updated whenever the referenced interface is changed.

Setup

To use existing mocks, no setup is required.

To generate new mocks, or update existing mocks, you need the mockgen tool:

go install github.com/golang/mock/mockgen
export PATH=$PATH:~/go/bin

Example: Updating mocks with go generate

For interfaces within cli_tools that require mocking, we create go generate definitions. These definitions codify naming convention, and simplify future updates.

For example, to update the mock for shell.Executor:

cd cli_tools/common/utils/shell
go generate ./...

Example: Update external mocks

For interfaces that are external to cli_tools, we run mockgen directly.

For example, to update the mock for daisy.Logger:

cd cli_tools/mocks
mockgen -package mocks -mock_names Logger=MockDaisyLogger \
  github.com/GoogleCloudPlatform/compute-daisy Logger  > mock_daisy_logger.go

Tips:

1. The headers of existing mocks typically include the package and interface names required to generate mocks.
2. To avoid namespace clashing, it may be required to use the -mock_names flag. Executing git diff will help you to determine whether that flag is required.

Best Practices

• If the mock will be used throughout *cli_tools, consider creating it in cli_tools/mocks.
• If the mock is used in a single place (to test a particular component), consider creating it near that component. For example: cli_tools/common/image/importer/mocks/source_mocks.go