[PM-34837] Add Detekt rule requiring named FontWeight constants

Add a detekt-rules module with a NamedFontWeight rule that reports
numeric weights such as FontWeight.W600 or FontWeight(600) and suggests
the named constant used in the Figma designs, such as FontWeight.SemiBold.

The module is added as a non-transitive detektPlugins dependency so
Detekt keeps its own Kotlin standard library and the root lockfile is
unchanged.

build.gradle.kts

@@ -35,6 +35,8 @@ configurations.configureEach {
 dependencies {
     detektPlugins(libs.detekt.detekt.formatting)
     detektPlugins(libs.detekt.detekt.rules)
+    // Bitwarden custom rules. Not transitive, so Detekt keeps its own Kotlin standard library.
+    detektPlugins(project(":detekt-rules")) { isTransitive = false }
 
     kover(project(":annotation"))
     kover(project(":app"))
@@ -59,6 +61,7 @@ detekt {
         "core/src",
         "cxf/src",
         "data/src",
+        "detekt-rules/src",
         "network/src",
         "testharness/src",
         "ui/src",

detekt-config.yml

@@ -667,3 +667,8 @@ style:
     active: true
     excludes: [ '**/test/**', '**/androidTest/**', '**/commonTest/**', '**/jvmTest/**', '**/jsTest/**', '**/iosTest/**' ]
     excludeImports: [ 'java.util.*', 'kotlinx.android.synthetic.*' ]
+
+bitwarden:
+  active: true
+  NamedFontWeight:
+    active: true

detekt-rules/.gitignore

@@ -0,0 +1 @@
+/build

detekt-rules/build.gradle.kts

@@ -0,0 +1,27 @@
+import org.jetbrains.kotlin.gradle.dsl.JvmTarget
+
+plugins {
+    // The Kotlin Gradle plugin is already on the root build classpath, so no version is needed.
+    id("org.jetbrains.kotlin.jvm")
+}
+
+java {
+    sourceCompatibility = JavaVersion.toVersion(libs.versions.jvmTarget.get())
+    targetCompatibility = JavaVersion.toVersion(libs.versions.jvmTarget.get())
+}
+
+kotlin {
+    compilerOptions {
+        jvmTarget.set(JvmTarget.fromTarget(libs.versions.jvmTarget.get()))
+    }
+}
+
+dependencies {
+    compileOnly(libs.detekt.detekt.api)
+
+    testImplementation(libs.detekt.detekt.api)
+    testImplementation(libs.detekt.detekt.test)
+    testImplementation(platform(libs.junit.bom))
+    testImplementation(libs.junit.jupiter)
+    testRuntimeOnly(libs.junit.platform.launcher)
+}

detekt-rules/src/main/kotlin/com/bitwarden/detekt/BitwardenRuleSetProvider.kt

@@ -0,0 +1,20 @@
+package com.bitwarden.detekt
+
+import io.gitlab.arturbosch.detekt.api.Config
+import io.gitlab.arturbosch.detekt.api.RuleSet
+import io.gitlab.arturbosch.detekt.api.RuleSetProvider
+
+/**
+ * Provides Bitwarden's custom Detekt rules.
+ */
+class BitwardenRuleSetProvider : RuleSetProvider {
+    override val ruleSetId: String = "bitwarden"
+
+    override fun instance(config: Config): RuleSet =
+        RuleSet(
+            id = ruleSetId,
+            rules = listOf(
+                NamedFontWeight(config),
+            ),
+        )
+}

detekt-rules/src/main/kotlin/com/bitwarden/detekt/NamedFontWeight.kt

@@ -0,0 +1,75 @@
+package com.bitwarden.detekt
+
+import io.gitlab.arturbosch.detekt.api.CodeSmell
+import io.gitlab.arturbosch.detekt.api.Config
+import io.gitlab.arturbosch.detekt.api.Debt
+import io.gitlab.arturbosch.detekt.api.Entity
+import io.gitlab.arturbosch.detekt.api.Issue
+import io.gitlab.arturbosch.detekt.api.Rule
+import io.gitlab.arturbosch.detekt.api.Severity
+import org.jetbrains.kotlin.psi.KtCallExpression
+import org.jetbrains.kotlin.psi.KtConstantExpression
+import org.jetbrains.kotlin.psi.KtDotQualifiedExpression
+import org.jetbrains.kotlin.psi.KtExpression
+
+/**
+ * Reports numeric `FontWeight` values, such as `FontWeight.W600` or `FontWeight(600)`, and
+ * suggests the named constant used in the Figma designs, such as `FontWeight.SemiBold`.
+ */
+class NamedFontWeight(config: Config) : Rule(config) {
+
+    override val issue: Issue = Issue(
+        id = javaClass.simpleName,
+        severity = Severity.Style,
+        description = "Use named FontWeight constants to match the Figma designs.",
+        debt = Debt.FIVE_MINS,
+    )
+
+    override fun visitDotQualifiedExpression(expression: KtDotQualifiedExpression) {
+        super.visitDotQualifiedExpression(expression)
+        if (!expression.receiverExpression.text.isFontWeight()) return
+        val selector = expression.selectorExpression?.text ?: return
+        if (!selector.startsWith(prefix = "W")) return
+        val weight = selector.removePrefix(prefix = "W").toIntOrNull() ?: return
+        reportIfNamed(expression = expression, current = "FontWeight.$selector", weight = weight)
+    }
+
+    override fun visitCallExpression(expression: KtCallExpression) {
+        super.visitCallExpression(expression)
+        if (expression.calleeExpression?.text?.isFontWeight() != true) return
+        val argument = expression.valueArguments.singleOrNull()?.getArgumentExpression()
+        val weight = (argument as? KtConstantExpression)?.text?.toIntOrNull() ?: return
+        reportIfNamed(expression = expression, current = "FontWeight($weight)", weight = weight)
+    }
+
+    private fun reportIfNamed(expression: KtExpression, current: String, weight: Int) {
+        val name = NAMED_WEIGHTS[weight] ?: return
+        report(
+            CodeSmell(
+                issue = issue,
+                entity = Entity.from(expression),
+                message = "Use FontWeight.$name instead of $current.",
+            ),
+        )
+    }
+
+    private fun String.isFontWeight(): Boolean =
+        this == FONT_WEIGHT || endsWith(suffix = ".$FONT_WEIGHT")
+
+    private companion object {
+        const val FONT_WEIGHT: String = "FontWeight"
+
+        @Suppress("MagicNumber")
+        val NAMED_WEIGHTS: Map<Int, String> = mapOf(
+            100 to "Thin",
+            200 to "ExtraLight",
+            300 to "Light",
+            400 to "Normal",
+            500 to "Medium",
+            600 to "SemiBold",
+            700 to "Bold",
+            800 to "ExtraBold",
+            900 to "Black",
+        )
+    }
+}

detekt-rules/src/main/resources/META-INF/services/io.gitlab.arturbosch.detekt.api.RuleSetProvider

@@ -0,0 +1 @@
+com.bitwarden.detekt.BitwardenRuleSetProvider

detekt-rules/src/main/resources/config/config.yml

@@ -0,0 +1,4 @@
+bitwarden:
+  active: true
+  NamedFontWeight:
+    active: true

detekt-rules/src/test/kotlin/com/bitwarden/detekt/NamedFontWeightTest.kt

@@ -0,0 +1,66 @@
+package com.bitwarden.detekt
+
+import io.gitlab.arturbosch.detekt.api.Config
+import io.gitlab.arturbosch.detekt.test.lint
+import org.junit.jupiter.api.Assertions.assertEquals
+import org.junit.jupiter.api.Test
+
+class NamedFontWeightTest {
+
+    private val rule = NamedFontWeight(Config.empty)
+
+    @Test
+    fun `numeric constant should be reported with the named replacement`() {
+        val findings = rule.lint("val weight = FontWeight.W600")
+
+        assertEquals(1, findings.size)
+        assertEquals(
+            "Use FontWeight.SemiBold instead of FontWeight.W600.",
+            findings.single().message,
+        )
+    }
+
+    @Test
+    fun `fully qualified numeric constant should be reported`() {
+        val findings = rule.lint("val weight = androidx.compose.ui.text.font.FontWeight.W400")
+
+        assertEquals(1, findings.size)
+        assertEquals(
+            "Use FontWeight.Normal instead of FontWeight.W400.",
+            findings.single().message,
+        )
+    }
+
+    @Test
+    fun `numeric constructor should be reported with the named replacement`() {
+        val findings = rule.lint("val weight = FontWeight(700)")
+
+        assertEquals(1, findings.size)
+        assertEquals("Use FontWeight.Bold instead of FontWeight(700).", findings.single().message)
+    }
+
+    @Test
+    fun `named constant should not be reported`() {
+        assertEquals(0, rule.lint("val weight = FontWeight.SemiBold").size)
+    }
+
+    @Test
+    fun `weight without a named constant should not be reported`() {
+        assertEquals(0, rule.lint("val weight = FontWeight(650)").size)
+    }
+
+    @Test
+    fun `weight property should not be reported`() {
+        assertEquals(0, rule.lint("val value = FontWeight.Bold.weight").size)
+    }
+
+    @Test
+    fun `numeric constants in a text style should each be reported`() {
+        val code = """
+            val style = TextStyle(fontWeight = FontWeight.W500)
+            val family = FontFamily(Font(1, weight = FontWeight.W900))
+        """.trimIndent()
+
+        assertEquals(2, rule.lint(code).size)
+    }
+}

gradle/libs.versions.toml

@@ -101,8 +101,10 @@ coil-coil = { module = "io.coil-kt.coil3:coil", version.ref = "coil" }
 coil-coil-compose = { module = "io.coil-kt.coil3:coil-compose", version.ref = "coil" }
 coil-coil-gif = { module = "io.coil-kt.coil3:coil-gif", version.ref = "coil" }
 coil-coil-network-okhttp = { module = "io.coil-kt.coil3:coil-network-okhttp", version.ref = "coil" }
+detekt-detekt-api = { module = "io.gitlab.arturbosch.detekt:detekt-api", version.ref = "detekt" }
 detekt-detekt-formatting = { module = "io.gitlab.arturbosch.detekt:detekt-formatting", version.ref = "detekt" }
 detekt-detekt-rules = { module = "io.gitlab.arturbosch.detekt:detekt-rules-libraries", version.ref = "detekt" }
+detekt-detekt-test = { module = "io.gitlab.arturbosch.detekt:detekt-test", version.ref = "detekt" }
 google-billing = { module = "com.android.billingclient:billing", version.ref = "googleBilling" }
 google-firebase-bom = { module = "com.google.firebase:firebase-bom", version.ref = "firebaseBom" }
 google-firebase-cloud-messaging = { module = "com.google.firebase:firebase-messaging" }

settings.gradle.kts

@@ -48,6 +48,7 @@ include(
     ":core",
     ":cxf",
     ":data",
+    ":detekt-rules",
     ":network",
     ":testharness",
     ":ui",