github.com/larhun/golden

golden

Package golden provides functions for testing commands using smart validation strings and gold master files.

A command must implement the Runner interface. It represents a black box system with inputs (the argument list) and outputs (the standard and error outputs, the panic and error messages, the exit code, and an optional file output). A test case is a value of Case type. It represents a set of input and output values. A test is performed using the Test function.

The following example tests a command named "hello" that should print "Hello World!" to its standard output with an argument list equal to []string{"hello", "World"} (the first argument must be the command name).

    var command Runner = ... // the "hello" command

    func TestXxx(t *testing.T) {
        Test(t, command, []Case{{
            Name:       "output",                   // test case name
            Args:       []string{"hello", "World"}, // argument list
            WantStdout: "Hello World!",             // expected standard output
        })
    }

The command under test may be implemented using inner functions or may be generated from an external hello program using the Program function:

    var command = Program("hello", nil)

The Test function supports smart validation strings and gold master files that define very flexible matches with a very simple syntax (see the package documentation for details). The "..." ellipsis is used to encode a partial match:

    "Hello..."     // match "Hello" prefix
    "...World!"    // match "World!" suffix
    "...World..."  // match "World" substring

The "^" and "$" delimiters are used to encode a pattern matching:

    "^.*(Hello|World).*$" // match "Hello" or "World" substring

The "golden" term is used to encode a value stored by a gold master file:

    "golden.json" // match file testdata/golden/TestXxx-output.json

The gold master pattern is commonly used when testing complex output: the expected string is saved to a file, the gold master, rather than to a validation string. All the gold masters used by TestXxx are updated by running the test with the update flag:

    go test -run TestXxx -update

All the gold masters are updates by running:

    go test -update

See the testing files for usage examples.