feat(lint): flag localized strings that still hold the base English text

auth/build.gradle.kts

@@ -152,6 +152,12 @@ dependencies {
     testImplementation(libs.kotlinx.serialization.json)
 
     debugImplementation(project(":internal:lintchecks"))
+
+    // Directly, not via :internal:lintchecks. That module declares lintChecks too, but
+    // lintChecks only applies to the module declaring it, and a debugImplementation
+    // dependency does not carry lint checks to the consumer — so the custom rules were never
+    // running here.
+    lintChecks(project(":internal:lint"))
 }
 
 kotlin {

auth/src/main/res/values-da/strings.xml

@@ -62,7 +62,8 @@
     <string name="fui_title_recover_password_activity">Gendan adgangskode</string>
     <string name="fui_title_confirm_recover_password">Tjek din mail.</string>
     <string name="fui_password_recovery_body">Få en vejledning sendt til denne mail om, hvordan du nulstiller din adgangskode.</string>
-    <string name="fui_button_text_send">Send</string>
+    <!-- Identical to English: this is the imperative of "sende". -->
+    <string name="fui_button_text_send" tools:ignore="UntranslatedResource">Send</string>
     <string name="fui_confirm_recovery_body">Følg vejledningen, der blev sendt til %1$s, for at gendanne din adgangskode.</string>
     <string name="fui_progress_dialog_sending">Sender…</string>
     <string name="fui_error_email_does_not_exist">Mailadressen matcher ikke en eksisterende konto</string>

auth/src/main/res/values-fil/strings.xml

@@ -6,11 +6,11 @@
     <string name="fui_tos_and_pp_footer">%1$s \u00A0 \u00A0 %2$s</string>
     <string name="fui_no_internet" translation_descripition="User message shown when sign-in is attempted while offline.">Error sa network, tingnan ang koneksyon mo sa internet.</string>
     <string name="fui_idp_name_google">Google</string>
-    <string name="fui_idp_name_facebook">Fecebook</string>
+    <string name="fui_idp_name_facebook">Facebook</string>
     <string name="fui_idp_name_twitter">Twitter</string>
     <string name="fui_idp_name_github">GitHub</string>
     <string name="fui_idp_name_phone">Telepono</string>
-    <string name="fui_idp_name_email">Email</string>
+    <string name="fui_idp_name_email" tools:ignore="UntranslatedResource">Email</string>
     <string name="fui_sign_in_with_google">Mag-sign in sa Google</string>
     <string name="fui_continue_with_google">Mag-sign in sa Google</string>
     <string name="fui_sign_in_with_facebook">Mag-sign in sa Facebook</string>
@@ -36,7 +36,7 @@
     <string name="fui_country_hint">Bansa</string>
     <string name="fui_country_selector_title" translation_description="Country selector modal title">Pumili ng bansa</string>
     <string name="fui_search_country_field_hint" translation_description="Hint for search for country input field">Maghanap ng bansa hal. +1, "US"</string>
-    <string name="fui_password_hint">Password</string>
+    <string name="fui_password_hint" tools:ignore="UntranslatedResource">Password</string>
     <string name="fui_new_password_hint">Bagong password</string>
     <string name="fui_required_field">Hindi mo ito maaaring iwanan na walang laman.</string>
     <string name="fui_invalid_email_address">Mali ang email address na iyon</string>

auth/src/main/res/values-it/strings.xml

@@ -10,7 +10,7 @@
     <string name="fui_idp_name_twitter">Twitter</string>
     <string name="fui_idp_name_github">GitHub</string>
     <string name="fui_idp_name_phone">Telefono</string>
-    <string name="fui_idp_name_email">Email</string>
+    <string name="fui_idp_name_email" tools:ignore="UntranslatedResource">Email</string>
     <string name="fui_sign_in_with_google">Accedi con Google</string>
     <string name="fui_continue_with_google">Accedi con Google</string>
     <string name="fui_sign_in_with_facebook">Accedi con Facebook</string>
@@ -36,7 +36,7 @@
     <string name="fui_country_hint">Paese</string>
     <string name="fui_country_selector_title" translation_description="Country selector modal title">Seleziona un paese</string>
     <string name="fui_search_country_field_hint" translation_description="Hint for search for country input field">Cerca paese ad es. +1, "US"</string>
-    <string name="fui_password_hint">Password</string>
+    <string name="fui_password_hint" tools:ignore="UntranslatedResource">Password</string>
     <string name="fui_new_password_hint">Nuova password</string>
     <string name="fui_required_field">Questo campo non può restare vuoto.</string>
     <string name="fui_invalid_email_address">L\'indirizzo email non è corretto</string>

auth/src/main/res/values-nb/strings.xml

@@ -62,7 +62,8 @@
     <string name="fui_title_recover_password_activity">Gjenopprett passordet</string>
     <string name="fui_title_confirm_recover_password">Sjekk e-posten din</string>
     <string name="fui_password_recovery_body">Få instruksjoner sendt til denne e-postadressen for hvordan du tilbakestiller passordet ditt.</string>
-    <string name="fui_button_text_send">Send</string>
+    <!-- Identical to English: this is the imperative of "sende". -->
+    <string name="fui_button_text_send" tools:ignore="UntranslatedResource">Send</string>
     <string name="fui_confirm_recovery_body">Følg veiledningen som er sendt til %1$s, for å gjenopprette passordet ditt.</string>
     <string name="fui_progress_dialog_sending">Sender…</string>
     <string name="fui_error_email_does_not_exist">Denne e-postadressen samsvarer ikke med en eksisterende konto</string>

auth/src/main/res/values-no/strings.xml

@@ -62,7 +62,8 @@
     <string name="fui_title_recover_password_activity">Gjenopprett passordet</string>
     <string name="fui_title_confirm_recover_password">Sjekk e-posten din</string>
     <string name="fui_password_recovery_body">Få instruksjoner sendt til denne e-postadressen for hvordan du tilbakestiller passordet ditt.</string>
-    <string name="fui_button_text_send">Send</string>
+    <!-- Identical to English: this is the imperative of "sende". -->
+    <string name="fui_button_text_send" tools:ignore="UntranslatedResource">Send</string>
     <string name="fui_confirm_recovery_body">Følg veiledningen som er sendt til %1$s, for å gjenopprette passordet ditt.</string>
     <string name="fui_progress_dialog_sending">Sender…</string>
     <string name="fui_error_email_does_not_exist">Denne e-postadressen samsvarer ikke med en eksisterende konto</string>

auth/src/main/res/values-pt-rPT/strings.xml

@@ -10,7 +10,7 @@
     <string name="fui_idp_name_twitter">Twitter</string>
     <string name="fui_idp_name_github">GitHub</string>
     <string name="fui_idp_name_phone">Telemóvel</string>
-    <string name="fui_idp_name_email">Email</string>
+    <string name="fui_idp_name_email" tools:ignore="UntranslatedResource">Email</string>
     <string name="fui_sign_in_with_google">Iniciar sessão com o Google</string>
     <string name="fui_continue_with_google">Iniciar sessão com o Google</string>
     <string name="fui_sign_in_with_facebook">Iniciar sessão com o Facebook</string>
@@ -31,7 +31,7 @@
     <string name="fui_sign_in_with_yahoo">Iniciar sessão com o Yahoo</string>
     <string name="fui_continue_with_yahoo">Iniciar sessão com o Yahoo</string>
     <string name="fui_next_default">Seguinte</string>
-    <string name="fui_email_hint">Email</string>
+    <string name="fui_email_hint" tools:ignore="UntranslatedResource">Email</string>
     <string name="fui_phone_hint">Número de telefone</string>
     <string name="fui_country_hint">País</string>
     <string name="fui_country_selector_title" translation_description="Country selector modal title">Selecione um país</string>

auth/src/main/res/values-tl/strings.xml

@@ -6,11 +6,11 @@
     <string name="fui_tos_and_pp_footer">%1$s \u00A0 \u00A0 %2$s</string>
     <string name="fui_no_internet" translation_descripition="User message shown when sign-in is attempted while offline.">Error sa network, tingnan ang koneksyon mo sa internet.</string>
     <string name="fui_idp_name_google">Google</string>
-    <string name="fui_idp_name_facebook">Fecebook</string>
+    <string name="fui_idp_name_facebook">Facebook</string>
     <string name="fui_idp_name_twitter">Twitter</string>
     <string name="fui_idp_name_github">GitHub</string>
     <string name="fui_idp_name_phone">Telepono</string>
-    <string name="fui_idp_name_email">Email</string>
+    <string name="fui_idp_name_email" tools:ignore="UntranslatedResource">Email</string>
     <string name="fui_sign_in_with_google">Mag-sign in sa Google</string>
     <string name="fui_continue_with_google">Mag-sign in sa Google</string>
     <string name="fui_sign_in_with_facebook">Mag-sign in sa Facebook</string>
@@ -36,7 +36,7 @@
     <string name="fui_country_hint">Bansa</string>
     <string name="fui_country_selector_title" translation_description="Country selector modal title">Pumili ng bansa</string>
     <string name="fui_search_country_field_hint" translation_description="Hint for search for country input field">Maghanap ng bansa hal. +1, "US"</string>
-    <string name="fui_password_hint">Password</string>
+    <string name="fui_password_hint" tools:ignore="UntranslatedResource">Password</string>
     <string name="fui_new_password_hint">Bagong password</string>
     <string name="fui_required_field">Hindi mo ito maaaring iwanan na walang laman.</string>
     <string name="fui_invalid_email_address">Mali ang email address na iyon</string>

internal/lint/build.gradle.kts

@@ -6,6 +6,7 @@ dependencies {
     compileOnly(libs.lint.api)
     compileOnly(libs.kotlin.stdlib)
 
+    testImplementation(libs.junit)
     testImplementation(libs.lint.api)
     testImplementation(libs.lint.tests)
 }

internal/lint/src/main/java/com/firebaseui/lint/internal/LintIssueRegistry.kt

@@ -11,7 +11,8 @@ class LintIssueRegistry : IssueRegistry() {
         get() = com.android.tools.lint.detector.api.CURRENT_API
 
     override val issues = listOf(
-        NonGlobalIdDetector.NON_GLOBAL_ID
+        NonGlobalIdDetector.NON_GLOBAL_ID,
+        UntranslatedResourceDetector.UNTRANSLATED_RESOURCE
     )
 
     override val vendor = Vendor(

internal/lint/src/main/java/com/firebaseui/lint/internal/UntranslatedResourceDetector.kt

@@ -0,0 +1,177 @@
+package com.firebaseui.lint.internal
+
+import com.android.SdkConstants.ATTR_NAME
+import com.android.SdkConstants.ATTR_TRANSLATABLE
+import com.android.SdkConstants.TAG_STRING
+import com.android.SdkConstants.VALUE_FALSE
+import com.android.ide.common.resources.configuration.FolderConfiguration
+import com.android.resources.ResourceFolderType
+import com.android.tools.lint.detector.api.Category
+import com.android.tools.lint.detector.api.Context
+import com.android.tools.lint.detector.api.Implementation
+import com.android.tools.lint.detector.api.Issue
+import com.android.tools.lint.detector.api.Location
+import com.android.tools.lint.detector.api.ResourceXmlDetector
+import com.android.tools.lint.detector.api.Scope
+import com.android.tools.lint.detector.api.Severity
+import com.android.tools.lint.detector.api.XmlContext
+import org.w3c.dom.Element
+
+/**
+ * Flags a string in a locale folder whose value is byte-identical to the base English one.
+ *
+ * `MissingTranslation` only fires when a string is *absent* from a locale, so a resource that
+ * was copied over untranslated is invisible to it: it is present, it just holds English. A
+ * whole class of shipped-in-English strings therefore never reaches a lint report; #2509
+ * removed 269 such values, found by scanning rather than by any gate.
+ *
+ * Only `<string>` elements are checked. An English copy of a `<plurals>` or `<string-array>`
+ * item is still invisible to this check as well as to `MissingTranslation`.
+ *
+ * English regional folders (`values-en-rGB` and friends) are skipped, as are strings marked
+ * `translatable="false"` and the [ALLOWED] names below. Anything else that is legitimately the
+ * same word in another language is suppressed at the site with `tools:ignore`, so the decision
+ * sits next to the string.
+ */
+class UntranslatedResourceDetector : ResourceXmlDetector() {
+
+    /** Base `values/strings.xml` text, keyed by resource name. */
+    private val baseStrings = mutableMapOf<String, String>()
+
+    /** Localized strings to judge once every resource file has been read. */
+    private val localized = mutableListOf<LocalizedString>()
+
+    private data class LocalizedString(
+        val name: String,
+        val folder: String,
+        val text: String,
+        val handle: Location.Handle
+    )
+
+    override fun appliesTo(folderType: ResourceFolderType): Boolean =
+        folderType == ResourceFolderType.VALUES
+
+    override fun getApplicableElements(): List<String> = listOf(TAG_STRING)
+
+    override fun visitElement(context: XmlContext, element: Element) {
+        val name = element.getAttribute(ATTR_NAME)
+        if (name.isEmpty()) return
+        if (element.getAttribute(ATTR_TRANSLATABLE) == VALUE_FALSE) return
+
+        // Compare rendered text rather than markup: a value that differs from the base only in
+        // its xliff placeholders is still untranslated copy.
+        val text = element.textContent.trim()
+        if (text.isEmpty()) return
+        if (!hasTranslatableWords(text)) return
+
+        val folderName = context.file.parentFile?.name ?: return
+
+        if (folderName == BASE_VALUES_FOLDER) {
+            // putIfAbsent rather than assignment: if a second source set ever contributes its
+            // own values/ folder, first-wins keeps the map from depending on traversal order.
+            baseStrings.putIfAbsent(name, text)
+            return
+        }
+
+        // Only the base folder above seeds the comparison. Any other unqualified folder
+        // (values-v26, values-sw360dp, a future values-night) is a configuration variant of the
+        // English copy, not a translation, so it is neither a source nor a candidate.
+        val locale = FolderConfiguration.getConfigForFolder(folderName)?.localeQualifier ?: return
+
+        if (locale.language == LANGUAGE_ENGLISH) return
+        if (name in ALLOWED) return
+
+        localized += LocalizedString(
+            name = name,
+            folder = folderName,
+            text = text,
+            handle = context.createLocationHandle(element)
+        )
+    }
+
+    override fun afterCheckRootProject(context: Context) {
+        // Nothing to compare against when lint runs over a single file, which is the IDE's
+        // incremental mode. Reporting there would flag every locale string in the file.
+        if (baseStrings.isEmpty()) return
+
+        for (string in localized) {
+            if (baseStrings[string.name] != string.text) continue
+            context.report(
+                UNTRANSLATED_RESOURCE,
+                string.handle.resolve(),
+                "\"${string.name}\" is the base English string in ${string.folder}, so it " +
+                    "ships untranslated. Translate it, or mark it `tools:ignore=" +
+                    "\"$ISSUE_ID\"` if the translation is genuinely identical."
+            )
+        }
+
+        baseStrings.clear()
+        localized.clear()
+    }
+
+    /**
+     * Whether [text] contains anything a translator could change.
+     *
+     * `fui_tos_and_pp_footer` is two format specifiers separated by non-breaking spaces, so it
+     * is necessarily identical in all 84 locale folders that define it. Strings made only of
+     * placeholders, punctuation and whitespace have no words to translate.
+     *
+     * Escape sequences are stripped first because they are spelled with letters. A non-breaking
+     * space is written in these files as a backslash followed by u00A0, and the u and the A in
+     * that sequence would otherwise read as translatable content.
+     */
+    private fun hasTranslatableWords(text: String): Boolean =
+        text.replace(UNICODE_ESCAPE, "")
+            .replace(FORMAT_SPECIFIER, "")
+            .any(Char::isLetter)
+
+    companion object {
+        private const val ISSUE_ID = "UntranslatedResource"
+        private const val LANGUAGE_ENGLISH = "en"
+        private const val BASE_VALUES_FOLDER = "values"
+
+        /** `%s`, `%d`, `%1$s` and friends. */
+        private val FORMAT_SPECIFIER = Regex("""%(\d+\$)?[-#+ 0,(]*\d*(\.\d+)?[a-zA-Z%]""")
+
+        /** Matches the escape sequence as written in the file, not the character it denotes. */
+        private val UNICODE_ESCAPE = Regex("""\\u[0-9a-fA-F]{4}""")
+
+        /**
+         * Names exempted wholesale, because suppressing them per folder would mean roughly 375
+         * `tools:ignore` attributes.
+         *
+         * The four `fui_idp_name_*` entries are brand names, which are not translated. Note this
+         * does make a regression invisible: if a locale ever replaced one with a mistranslation,
+         * nothing here would report it. That is not hypothetical. `values-fil` and `values-tl`
+         * spelled `fui_idp_name_facebook` as `Fecebook` from the original translation import
+         * (#771) until this change corrected it, and an exemption is exactly why no gate would
+         * have caught it.
+         *
+         * `fui_mfa_method_sms` is a **provisional** exemption and not the same kind of entry.
+         * "SMS" is genuinely translated in several locales (`رسالة نصية` in `ar`, `短信` in `zh`,
+         * `СМС` in `sr`), so the 70 folders that carry the bare English acronym are real hits
+         * this silences. It is exempted only because the string is unreferenced dead copy that
+         * CPRN-445 is expected to delete; when that lands, drop this entry rather than keeping
+         * it.
+         */
+        private val ALLOWED = setOf(
+            "fui_idp_name_facebook",
+            "fui_idp_name_github",
+            "fui_idp_name_google",
+            "fui_idp_name_twitter",
+            "fui_mfa_method_sms"
+        )
+
+        val UNTRANSLATED_RESOURCE = Issue.create(
+            ISSUE_ID,
+            "Localized string still holds the base English text",
+            "A string that is present in a locale folder but identical to the base English " +
+                "value ships as English to users of that locale. `MissingTranslation` cannot " +
+                "catch this, because it only reports strings that are absent.",
+            Category.MESSAGES,
+            6,
+            Severity.ERROR,
+            Implementation(UntranslatedResourceDetector::class.java, Scope.ALL_RESOURCES_SCOPE)
+        )
+    }
+}

internal/lint/src/test/java/com/firebaseui/lint/internal/LintTestSdk.kt

@@ -0,0 +1,44 @@
+package com.firebaseui.lint.internal
+
+import com.android.tools.lint.checks.infrastructure.TestLintTask
+import java.io.File
+import java.util.Properties
+
+/**
+ * Points [TestLintTask] at the local Android SDK.
+ *
+ * Lint's test harness refuses to run without one, and Gradle does not put `ANDROID_HOME` into
+ * the test JVM's environment. The previous approach scanned `java.library.path` for a segment
+ * containing "SDK", splitting on `;`, which only ever resolved on Windows: on macOS and Linux
+ * it silently found nothing, the SDK went unconfigured, and every test in this module failed
+ * with "This test requires an Android SDK".
+ */
+internal fun TestLintTask.withLocalSdk(): TestLintTask {
+    val sdk = androidSdkHome() ?: error(
+        "No Android SDK found. Set ANDROID_HOME, or add sdk.dir to local.properties at the " +
+            "repository root."
+    )
+    return sdkHome(sdk)
+}
+
+private fun androidSdkHome(): File? {
+    val fromEnv = sequenceOf("ANDROID_HOME", "ANDROID_SDK_ROOT")
+        .mapNotNull { System.getenv(it) }
+        .map(::File)
+        .firstOrNull(File::isDirectory)
+    if (fromEnv != null) return fromEnv
+
+    // Tests run with the module directory as the working directory, so walk up to the root.
+    var dir: File? = File(".").absoluteFile
+    while (dir != null) {
+        val properties = File(dir, "local.properties")
+        if (properties.isFile) {
+            val sdkDir = properties.inputStream().use { Properties().apply { load(it) } }
+                .getProperty("sdk.dir")
+                ?.let(::File)
+            if (sdkDir?.isDirectory == true) return sdkDir
+        }
+        dir = dir.parentFile
+    }
+    return null
+}