Summary

• PermissionsDispatcher now have a custom lint
• Adding custom lint is not that hard
• LintDetectorTest…? Forget it

PermissionsDispatcher now have a custom lint

First of all, I am one of collaborators of PermissionsDispatcher which makes developers handle runtime permissions very easily.

PermissionsDispatcher now have a custom lint for its library. Initial issue came from this comment.

The library requires the developer to define a method with @NeedsPermission. Like this

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@NeedsPermission(Manifest.permission.CAMERA)
void showCamera() {
}

However, this method should not directly access. Instead, the developers must use a method that PermissionsDispatcher generated.

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void foo() {
    MainActivityPermissionsDispatcher.showCameraWithCheck(this); // Yes
}

void foo2() {
    showCamera(); // No!
}

In order to make sure the developers did not call this method, we decide to provide custom lint for this library.

How to add custom lint for library

To create custom lint for Android application, check links below

• Writing Custom Lint Rules
• Writing a Lint Check
• @hotchime’s blog post at qiita (For Japanese developer)

Custom lint for library needs extra settings to inject lint.jar to its .aar file

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configurations {
    lintChecks
}

dependencies {
    ...

    // we have lint module with lintCheck configuration.
    // check this file: https://github.com/shiraji/PermissionsDispatcher/blob/master/lint/build.gradle
    lintChecks project(path: ':lint', configuration: 'lintChecks')
}

assemble.doLast {
    copyJarToOtherModules.execute()
}

task copyLintJar(type: Copy) {
    from(configurations.lintChecks) {
        rename { 'lint.jar' }
    }
    into 'build/intermediates/lint/'
}

project.afterEvaluate {
    def compileLintTask = project.tasks.find { it.name == 'compileLint' }
    compileLintTask.dependsOn(copyLintJar)
}

Basically, if there is compileLint task, then make the task depends on copyLintJar task which copies lint.jar to build/intermediates/lint/

The user of this library doesn’t need to put lint.jar to .android/lint/. Just sync library and then run ./gradlew lint

Use LintDetectorTest

Just don’t.

Check this code

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File f = new File(root,
            "tools/base/lint/libs/lint-tests/src/test/java/".replace('/', File.separatorChar)
            + pkg.replace('.', File.separatorChar)
            + File.separatorChar + path);

This is the code that reads from $ROOT/tools/base/lint/libs/lint-tests/src/test/java/PACAKGE-NAME-REPLACE-DOT-WITH-SLASH. I believe most developers doesn’t want to put project in the specific directory in order to pass the test cases.

Actually, current version of LintDetectorTest has a lots of problems with loading resources, java source and “class” file. (Yes! you need to supply .class file to run the test)

In order to use the LintDetectorTest, the developer must override protected InputStream getTestResource(String relativePath, boolean expectExists) like what AOSP did

LintDetectorTest is still Beta. I assumed there are a lot of work to make it production release.

If it comes to production, I hope it does not require me to pass .java/.class file like this way.

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lintFiles("MainActivity.class=>pkg/MainActivity.class"));

Now how to test???

I don’t know.

The only way I came up is manual testing.

So, someone who know better way to test lint, please let me know!