For #8947 - Lint check for licenses in Kotlin/Java source files (#15639)

mozilla-lint-rules/build.gradle

@@ -12,6 +12,9 @@ dependencies {
     compileOnly "org.jetbrains.kotlin:kotlin-stdlib:${Versions.kotlin}"
     compileOnly "com.android.tools.lint:lint-api:${Versions.android_lint_api}"
     compileOnly "com.android.tools.lint:lint-checks:${Versions.android_lint_api}"
+
+    testImplementation "com.android.tools.lint:lint:${Versions.android_lint_api}"
+    testImplementation "com.android.tools.lint:lint-tests:${Versions.android_lint_api}"
 }
 
 jar {

mozilla-lint-rules/src/main/java/org/mozilla/fenix/lintrules/LicenseCommentChecker.kt

@@ -0,0 +1,84 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.lintrules
+
+import com.android.tools.lint.client.api.UElementHandler
+import com.android.tools.lint.detector.api.JavaContext
+import com.android.tools.lint.detector.api.LintFix
+import org.jetbrains.kotlin.psi.psiUtil.siblings
+import org.jetbrains.kotlin.psi.psiUtil.startsWithComment
+import org.jetbrains.uast.UComment
+import org.jetbrains.uast.UFile
+
+class LicenseCommentChecker(private val context: JavaContext) : UElementHandler() {
+
+    companion object {
+        val ValidLicenseForKotlinFiles = """
+            |/* This Source Code Form is subject to the terms of the Mozilla Public
+            | * License, v. 2.0. If a copy of the MPL was not distributed with this
+            | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */""".trimMargin()
+    }
+
+    override fun visitFile(node: UFile) {
+        if (!node.sourcePsi.startsWithComment()) {
+            reportMissingLicense(node)
+        } else {
+            val firstComment = node.allCommentsInFile.first()
+            if (firstComment.text != ValidLicenseForKotlinFiles) {
+                reportInvalidLicenseFormat(firstComment)
+            } else {
+                val nextSibling =
+                    firstComment.sourcePsi.siblings(withItself = false).firstOrNull()
+                if (nextSibling?.text != "\n\n") {
+                    reportMissingLeadingNewLineCharacter(firstComment)
+                }
+            }
+        }
+    }
+
+    private fun reportMissingLicense(node: UFile) = context.report(
+        LicenseDetector.ISSUE_MISSING_LICENSE,
+        context.getLocation(node.sourcePsi.firstChild),
+        "The file must start with a comment containing the license",
+        addLicenseQuickFix()
+    )
+
+    private fun reportInvalidLicenseFormat(comment: UComment) = context.report(
+        LicenseDetector.ISSUE_INVALID_LICENSE_FORMAT,
+        context.getLocation(comment),
+        "The license comment doesn't have the appropriate format",
+        replaceCommentWithValidLicenseFix(comment)
+    )
+
+    private fun reportMissingLeadingNewLineCharacter(licenseComment: UComment) = context.report(
+        LicenseDetector.ISSUE_INVALID_LICENSE_FORMAT,
+        context.getRangeLocation(licenseComment, licenseComment.text.lastIndex, 1),
+        "The license comment must be followed by a newline character",
+        addLeadingNewLineQuickFix(licenseComment)
+    )
+
+    private fun addLicenseQuickFix() = LintFix.create()
+        .name("Insert license at the top of the file")
+        .replace()
+        .beginning()
+        .with(ValidLicenseForKotlinFiles + "\n\n")
+        .autoFix()
+        .build()
+
+    private fun replaceCommentWithValidLicenseFix(comment: UComment) = LintFix.create()
+        .name("Replace with correctly formatted license")
+        .replace()
+        .range(context.getLocation(comment))
+        .with(ValidLicenseForKotlinFiles)
+        .build()
+
+    private fun addLeadingNewLineQuickFix(licenseComment: UComment) = LintFix.create()
+        .name("Insert newline character after the license")
+        .replace()
+        .range(context.getLocation(licenseComment))
+        .with(ValidLicenseForKotlinFiles + "\n")
+        .autoFix()
+        .build()
+}

mozilla-lint-rules/src/main/java/org/mozilla/fenix/lintrules/LicenseDetector.kt

@@ -0,0 +1,46 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.lintrules
+
+import com.android.tools.lint.client.api.UElementHandler
+import com.android.tools.lint.detector.api.*
+import org.jetbrains.uast.UElement
+import org.jetbrains.uast.UFile
+
+class LicenseDetector : Detector(), SourceCodeScanner {
+
+    companion object {
+
+        private val Implementation = Implementation(
+            LicenseDetector::class.java,
+            Scope.JAVA_FILE_SCOPE
+        )
+
+        val ISSUE_MISSING_LICENSE = Issue.create(
+            id = "MissingLicense",
+            briefDescription = "File doesn't start with the license comment",
+            explanation = "Every file must start with the license comment:\n" +
+                    LicenseCommentChecker.ValidLicenseForKotlinFiles,
+            category = Category.CORRECTNESS,
+            severity = Severity.WARNING,
+            implementation = Implementation
+        )
+
+        val ISSUE_INVALID_LICENSE_FORMAT = Issue.create(
+            id = "InvalidLicenseFormat",
+            briefDescription = "License isn't formatted correctly",
+            explanation = "The license must be:\n${LicenseCommentChecker.ValidLicenseForKotlinFiles}",
+            category = Category.CORRECTNESS,
+            severity = Severity.WARNING,
+            implementation = Implementation
+        )
+    }
+
+    override fun getApplicableUastTypes(): List<Class<out UElement>>? = listOf(UFile::class.java)
+
+    override fun createUastHandler(context: JavaContext): UElementHandler? =
+        LicenseCommentChecker(context)
+
+}

mozilla-lint-rules/src/main/java/org/mozilla/fenix/lintrules/LintIssueRegistry.kt

@@ -17,6 +17,8 @@ class LintIssueRegistry : IssueRegistry() {
         ButtonStyleXmlDetector.ISSUE_XML_STYLE,
         AndroidSrcXmlDetector.ISSUE_XML_SRC_USAGE,
         TextViewAndroidSrcXmlDetector.ISSUE_XML_SRC_USAGE,
-        ImageViewAndroidTintXmlDetector.ISSUE_XML_SRC_USAGE
+        ImageViewAndroidTintXmlDetector.ISSUE_XML_SRC_USAGE,
+        LicenseDetector.ISSUE_MISSING_LICENSE,
+        LicenseDetector.ISSUE_INVALID_LICENSE_FORMAT
     ) + ConstraintLayoutPerfDetector.ISSUES
 }

mozilla-lint-rules/src/test/java/org/mozilla/fenix/lintrules/LicenseDetectorTest.kt

@@ -0,0 +1,140 @@
+/* This Source Code Form is subject to the terms of the Mozilla Public
+ * License, v. 2.0. If a copy of the MPL was not distributed with this
+ * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+
+package org.mozilla.fenix.lintrules
+
+import com.android.tools.lint.checks.infrastructure.TestFiles
+import com.android.tools.lint.checks.infrastructure.TestLintTask.lint
+import org.junit.Test
+import org.mozilla.fenix.lintrules.LicenseCommentChecker.Companion.ValidLicenseForKotlinFiles
+import org.mozilla.fenix.lintrules.LicenseDetector.Companion.ISSUE_INVALID_LICENSE_FORMAT
+import org.mozilla.fenix.lintrules.LicenseDetector.Companion.ISSUE_MISSING_LICENSE
+
+class LicenseDetectorTest {
+
+    @Test
+    fun `report missing license if it isn't at the top of the file`() {
+        val code = """
+            |package example
+            |
+            |class SomeExample {
+            |   fun test() {
+            |       val x = 10
+            |       println("Hello")
+            |   }
+            |}""".trimMargin()
+
+        val expectedReport = """
+            |src/example/SomeExample.kt:1: Warning: The file must start with a comment containing the license [MissingLicense]
+            |package example
+            |~~~~~~~~~~~~~~~
+            |0 errors, 1 warnings""".trimMargin()
+
+        val expectedFixOutput = """
+            |Fix for src/example/SomeExample.kt line 1: Insert license at the top of the file:
+            |@@ -1 +1
+            |+ /* This Source Code Form is subject to the terms of the Mozilla Public
+            |+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+            |+  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+            |+""".trimMargin()
+
+        lint()
+            .files(TestFiles.kt(code))
+            .issues(ISSUE_MISSING_LICENSE, ISSUE_INVALID_LICENSE_FORMAT)
+            .run()
+            .expect(expectedReport)
+            .expectFixDiffs(expectedFixOutput)
+    }
+
+    @Test
+    fun `report invalid license format if it doesn't have a leading newline character`() {
+        val code = """
+            |$ValidLicenseForKotlinFiles
+            |package example
+            |
+            |class SomeExample {
+            |    fun test() {
+            |        val x = 10
+            |        println("Hello")
+            |    }
+            |}""".trimMargin()
+
+        val expectedReport = """
+            |src/example/SomeExample.kt:3: Warning: The license comment must be followed by a newline character [InvalidLicenseFormat]
+            | * file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+            |                                                             ~
+            |0 errors, 1 warnings""".trimMargin()
+
+        val expectedFixOutput = """
+            |Fix for src/example/SomeExample.kt line 3: Insert newline character after the license:
+            |@@ -4 +4
+            |+""".trimMargin()
+
+        lint()
+            .files(TestFiles.kt(code))
+            .issues(ISSUE_MISSING_LICENSE, ISSUE_INVALID_LICENSE_FORMAT)
+            .run()
+            .expect(expectedReport)
+            .expectFixDiffs(expectedFixOutput)
+    }
+
+    @Test
+    fun `valid license does not generate a warning`() {
+        val code = """
+            |$ValidLicenseForKotlinFiles
+            |
+            |package example
+            |
+            |class SomeExample {
+            |    fun test() {
+            |        val x = 10
+            |        println("Hello")
+            |    }
+            |}""".trimMargin()
+
+        lint()
+            .files(TestFiles.kt(code))
+            .issues(ISSUE_MISSING_LICENSE, ISSUE_INVALID_LICENSE_FORMAT)
+            .run()
+            .expectClean()
+    }
+
+    @Test
+    fun `report incorrectly formatted license`() {
+        val code = """
+            |/* This Source Code Form is subject to the terms of the Mozilla Public
+            |   License, v. 2.0. If a copy of the MPL was not distributed with this
+            |   file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+            |
+            |package example
+            |
+            |class SomeExample {
+            |    fun test() {
+            |        val x = 10
+            |        println("Hello")
+            |    }
+            |}""".trimMargin()
+
+        val expectedReport = """
+            |src/example/SomeExample.kt:1: Warning: The license comment doesn't have the appropriate format [InvalidLicenseFormat]
+            |/* This Source Code Form is subject to the terms of the Mozilla Public
+            |^
+            |0 errors, 1 warnings""".trimMargin()
+
+        val expectedFixOutput = """
+            |Fix for src/example/SomeExample.kt line 1: Replace with correctly formatted license:
+            |@@ -2 +2
+            |-    License, v. 2.0. If a copy of the MPL was not distributed with this
+            |-    file, You can obtain one at http://mozilla.org/MPL/2.0/. */
+            |+  * License, v. 2.0. If a copy of the MPL was not distributed with this
+            |+  * file, You can obtain one at http://mozilla.org/MPL/2.0/. */""".trimMargin()
+
+        lint()
+            .files(TestFiles.kt(code))
+            .issues(ISSUE_MISSING_LICENSE, ISSUE_INVALID_LICENSE_FORMAT)
+            .run()
+            .expect(expectedReport)
+            .expectFixDiffs(expectedFixOutput)
+    }
+}