(#) Suspicious default value to 'UNKNOWN' for a Moshi enum !!! ERROR: Suspicious default value to 'UNKNOWN' for a Moshi enum This is an error. Id : `MoshiUsageEnumPropertyDefaultUnknown` Summary : Suspicious default value to 'UNKNOWN' for a Moshi enum Severity : Error Category : Correctness Platform : Any Vendor : slack Identifier : slack-lint Contact : https://github.com/slackhq/slack-lints Feedback : https://github.com/slackhq/slack-lints Min : Lint 8.7+ Compiled : Lint 8.7+ Artifact : [com.slack.lint:slack-lint-checks](com_slack_lint_slack-lint-checks.md.html) Since : 0.1.0 Affects : Kotlin and Java files and test sources Editing : This check runs on the fly in the IDE editor Implementation : [Source Code](https://github.com/slackhq/slack-lints/tree/main/slack-lint-checks/src/main/java/slack/lint/MoshiUsageDetector.kt) Tests : [Source Code](https://github.com/slackhq/slack-lints/tree/main/slack-lint-checks/src/test/java/slack/lint/MoshiUsageDetectorTest.kt) Copyright Year : 2021 The enum type of this property is handled by Moshi. This means it will default to 'UNKNOWN' if an unrecognized enum is encountered in decoding. At best, it is redundant to default a property to this value. At worst, it can change nullability semantics if the enum should actually allow nullable values or null on absence. !!! Tip This lint check has an associated quickfix available in the IDE. (##) Example Here is an example of lint warnings produced by this check: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~text src/slack/model/Example.kt:9:Error: Suspicious default value to 'UNKNOWN' for a Moshi enum. [MoshiUsageEnumPropertyDefaultUnknown] val value3: TestEnum? = UNKNOWN, ------- src/slack/model/Example.kt:10:Error: Suspicious default value to 'UNKNOWN' for a Moshi enum. [MoshiUsageEnumPropertyDefaultUnknown] val value4: TestEnum = UNKNOWN, ------- src/slack/model/Example.kt:11:Error: Suspicious default value to 'UNKNOWN' for a Moshi enum. [MoshiUsageEnumPropertyDefaultUnknown] val value5: TestEnum = TestEnum.UNKNOWN, ---------------- ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ Here is the source file referenced above: `src/slack/model/Example.kt`: ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~kotlin linenumbers package slack.model import com.squareup.moshi.JsonClass @JsonClass(generateAdapter = true) data class Example( val value1: TestEnum?, val value2: TestEnum? = null, val value3: TestEnum? = UNKNOWN, val value4: TestEnum = UNKNOWN, val value5: TestEnum = TestEnum.UNKNOWN, ) @JsonClass(generateAdapter = false) enum class TestEnum { UNKNOWN, VALUE } ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ You can also visit the [source code](https://github.com/slackhq/slack-lints/tree/main/slack-lint-checks/src/test/java/slack/lint/MoshiUsageDetectorTest.kt) for the unit tests for this check to see additional scenarios. The above example was automatically extracted from the first unit test found for this lint check, `MoshiUsageDetector.enum_prop_default_unknown`. To report a problem with this extracted sample, visit https://github.com/slackhq/slack-lints. (##) Including !!! This is not a built-in check. To include it, add the below dependency to your project. This lint check is included in the lint documentation, but the Android team may or may not agree with its recommendations. ``` // build.gradle.kts lintChecks("com.slack.lint:slack-lint-checks:0.9.0") // build.gradle lintChecks 'com.slack.lint:slack-lint-checks:0.9.0' // build.gradle.kts with version catalogs: lintChecks(libs.slack.lint.checks) # libs.versions.toml [versions] slack-lint-checks = "0.9.0" [libraries] # For clarity and text wrapping purposes the following declaration is # shown split up across lines, but in TOML it needs to be on a single # line (see https://github.com/toml-lang/toml/issues/516) so adjust # when pasting into libs.versions.toml: slack-lint-checks = { module = "com.slack.lint:slack-lint-checks", version.ref = "slack-lint-checks" } ``` 0.9.0 is the version this documentation was generated from; there may be newer versions available. [Additional details about com.slack.lint:slack-lint-checks](com_slack_lint_slack-lint-checks.md.html). (##) Suppressing You can suppress false positives using one of the following mechanisms: * Using a suppression annotation like this on the enclosing element: ```kt // Kotlin @Suppress("MoshiUsageEnumPropertyDefaultUnknown") fun method() { problematicStatement() } ``` or ```java // Java @SuppressWarnings("MoshiUsageEnumPropertyDefaultUnknown") void method() { problematicStatement(); } ``` * Using a suppression comment like this on the line above: ```kt //noinspection MoshiUsageEnumPropertyDefaultUnknown problematicStatement() ``` * Using a special `lint.xml` file in the source tree which turns off the check in that folder and any sub folder. A simple file might look like this: ```xml <?xml version="1.0" encoding="UTF-8"?> <lint> <issue id="MoshiUsageEnumPropertyDefaultUnknown" severity="ignore" /> </lint> ``` Instead of `ignore` you can also change the severity here, for example from `error` to `warning`. You can find additional documentation on how to filter issues by path, regular expression and so on [here](https://googlesamples.github.io/android-custom-lint-rules/usage/lintxml.md.html). * In Gradle projects, using the DSL syntax to configure lint. For example, you can use something like ```gradle lintOptions { disable 'MoshiUsageEnumPropertyDefaultUnknown' } ``` In Android projects this should be nested inside an `android { }` block. * For manual invocations of `lint`, using the `--ignore` flag: ``` $ lint --ignore MoshiUsageEnumPropertyDefaultUnknown ...` ``` * Last, but not least, using baselines, as discussed [here](https://googlesamples.github.io/android-custom-lint-rules/usage/baselines.md.html).