GIDL

GIDL is a code generation tool to create Golden FIDL Tests. It generates code that tests whether FIDL bindings correctly encode and decode FIDL to/from the wire format. Standard .fidl files define the FIDL data structures, and .gidl files use those data structures and define the expected bytes for the wire-format. The gidl tool reads theses .gidl files, and outputs conformance tests that verifies the FIDL definitions match their expected wire-format bytes.

GIDL supports multiple languages, and will generate a conformance test for each supported language.

Structure

• parser: Code for parsing GIDL syntax into the IR (see next item).
• ir: The in memory representation of a suite of GIDL tests. For example, it defines types to represent each type of test: success, encode/decode_success/failure.
• mixer: Provides a Schema that wraps the FIDL IR. The mixer is responsible for validating that FIDL value in GIDL match their corresponding type declaration
• Backends (cpp, dart, etc.): Each backend takes in GIDL IR and FIDL IR, validates it using the mixer, and outputs the target language specific tests.

Using GIDL

The input files for GIDL are at <//src/tests/fidl/conformance_suite/>. That directory contains multiple .gidl and .fidl files.

Testing gidl:

fx test //tools/fidl/gidl

Testing gidl and all conformance tests:

fidldev test gidl

Refer to the FIDL contributing doc for how to set up fidldev.

To run conformance tests in a specific binding, you can use --dry-run to print out the test command for all of the conformance tests, then pick out the ones you want to run:

fidldev test gidl --dry-run

Writing Conformance Tests

There are three kinds of tests which can be expressed. We describe them below.

Success

A success test case captures a value (optionally with handles), and its wire format representation.

Here is an example:

// Assuming the following FIDL definition:
//
// struct OneStringOfMaxLengthFive {
//     string:5 the_string;
// };

success("OneStringOfMaxLengthFive-empty") {
    value = OneStringOfMaxLengthFive {
        the_string: "",
    }
    bytes = {
        0, 0, 0, 0, 0, 0, 0, 0, // length
        255, 255, 255, 255, 255, 255, 255, 255, // alloc present
    }
}

From this description, the following must be verified:

• Encoding of the value into bytes
• Decoding of the bytes into the value
• Round-trips from value to bytes, back to value, back to bytes