TestNativePlatform.fromJson constructor

@visibleForTesting TestNativePlatform.fromJson(String jsonText)

Creates a new TestNativePlatform with properties from a JSON string.

The jsonText must be a valid JSON string representing a JSON object, and the values for the NativePlatform properties are extracted from the object's values for keys with the properties' names.

Example:

var testNativePlatform = TestNativePlatform.fromJson('''{
  "operatingSystem": "linux",
  "operatingSystemVersion": "MockVersion.2.3",
  "numberOfProcessors": 42,
  "lineTerminator": "\r",
  "packageConfig": null
}''')'

The JSON object's value for such a key must be either a string or null.

Throws a FormatException if the jsonText string is not valid JSON text, or the JSON text does not represent a JSON object. The property values must have the correct type for the corresponding NativePlatform property, or be null. If the map value of a property key is not a string, integer, boolean, list of strings, or map with string keys and values, as required by the corresponding property, a FormatException is also thrown.

Other keys are ignored. Missing property keys, or keys with a null value, leave the property undefined.

The toJson method will leave out undefined properties, so TestNativePlatform.fromJson(TestNativePlatform.toJson()) can create an exact copy at a later time. (To create a copy right now, TestNativePlatform.copyWith() is easier and more efficient.)

Implementation

@visibleForTesting
factory TestNativePlatform.fromJson(String jsonText) {
  Object? jsonObject = jsonDecode(jsonText);
  if (jsonObject is! Map<String, Object?>) {
    throw FormatException('Not a JSON object', jsonText);
  }

  // Read out the values that require special validation first.
  var environment = _getJsonProperty<Map<String, Object?>>(
    jsonObject,
    json_key.environment,
    jsonText,
  );
  var executableArguments = _getJsonProperty<List<Object?>>(
    jsonObject,
    json_key.executableArguments,
    jsonText,
  );
  var script = _getJsonProperty<String>(jsonObject, 'script', jsonText);

  return TestNativePlatform(
    // Check that environment values are strings. Filter out null values.
    environment: environment == null
        ? null
        : <String, String>{
            for (var MapEntry(:key, :value) in environment.entries)
              if (value != null)
                key: (value is String
                    ? value
                    : _failJsonParse<String>(
                        'environment[$key]',
                        value,
                        jsonText,
                      )),
          },
    executable: _getJsonProperty<String>(
      jsonObject,
      json_key.executable,
      jsonText,
    ),
    // Check the executable arguments are strings.
    executableArguments: executableArguments == null
        ? null
        : <String>[
            for (var argument in executableArguments)
              argument is String
                  ? argument
                  : _failJsonParse<String>(
                      'executableArguments',
                      argument,
                      jsonText,
                    ),
          ],
    lineTerminator: _getJsonProperty<String>(
      jsonObject,
      json_key.lineTerminator,
      jsonText,
    ),
    localeName: _getJsonProperty<String>(
      jsonObject,
      json_key.localeName,
      jsonText,
    ),
    localHostname: _getJsonProperty<String>(
      jsonObject,
      json_key.localHostname,
      jsonText,
    ),
    numberOfProcessors: _getJsonProperty<int>(
      jsonObject,
      json_key.numberOfProcessors,
      jsonText,
    ),
    operatingSystem: _getJsonProperty<String>(
      jsonObject,
      json_key.operatingSystem,
      jsonText,
    ),
    operatingSystemVersion: _getJsonProperty<String>(
      jsonObject,
      json_key.operatingSystemVersion,
      jsonText,
    ),
    packageConfig: _getJsonProperty<String>(
      jsonObject,
      json_key.packageConfig,
      jsonText,
    ),
    pathSeparator: _getJsonProperty<String>(
      jsonObject,
      json_key.pathSeparator,
      jsonText,
    ),
    resolvedExecutable: _getJsonProperty<String>(
      jsonObject,
      json_key.resolvedExecutable,
      jsonText,
    ),
    // Checks that the script is a valid URI.
    script: script == null ? null : Uri.parse(script),
    stdinSupportsAnsi: _getJsonProperty<bool>(
      jsonObject,
      json_key.stdinSupportsAnsi,
      jsonText,
    ),
    stdoutSupportsAnsi: _getJsonProperty<bool>(
      jsonObject,
      json_key.stdoutSupportsAnsi,
      jsonText,
    ),
    version: _getJsonProperty<String>(jsonObject, json_key.version, jsonText),
  );
}