Fix UnknownFormatConversionException (#13162)

* Fix UnknownFormatConversionException when user input contains percent signs

StaticResolvableString.resolve() called String.format(value, ...) unconditionally,
treating the value as a format string. When the value is raw user input (e.g. from
a text field whose contentDescription is built via String.resolvableString), any
percent sign sequence such as "%@" causes a java.util.UnknownFormatConversionException.

Fix: skip String.format when the args list is empty. All String.resolvableString
usages pass emptyList() for args, so no formatting is ever needed — the value
should be returned as-is.

Adds regression tests in ResolvableStringTest covering format specifiers in
no-arg static strings, and a test in CvcControllerTest confirming that
contentDescription resolves without throwing when the CVC field contains "%@".

Committed-By-Agent: goose

* Address PR review feedback

Committed-By-Agent: codex
Co-authored-by: codex <noreply@openai.com>

---------

Co-authored-by: codex <noreply@openai.com>

Author: gbirch-stripe

stripe-core/src/main/java/com/stripe/android/core/strings/StaticResolvableString.kt

@@ -11,6 +11,11 @@ internal data class StaticResolvableString(
 ) : ResolvableString {
     @Suppress("SpreadOperator")
     override fun resolve(context: Context): String {
-        return value.format(*resolveArgs(context, args))
+        val resolved = resolveArgs(context, args)
+        // Avoid running String.format when there are no args: the value may be raw user input
+        // containing percent signs (e.g. "%@", "50%"), which would cause a
+        // java.util.UnknownFormatConversionException if passed through String.format as a
+        // format string.
+        return if (resolved.isEmpty()) value else value.format(*resolved)
     }
 }

stripe-core/src/test/java/com/stripe/android/core/strings/ResolvableStringTest.kt

@@ -2,6 +2,7 @@ package com.stripe.android.core.strings
 
 import android.os.Bundle
 import android.os.Parcel
+import androidx.test.core.app.ApplicationProvider
 import androidx.test.runner.AndroidJUnit4
 import com.stripe.android.core.strings.transformations.Replace
 import org.junit.Test
@@ -102,6 +103,25 @@ class ResolvableStringTest {
         )
     }
 
+    @Test
+    fun `static resolvable string with format specifier in value and no args resolves without error`() {
+        val context = ApplicationProvider.getApplicationContext<android.content.Context>()
+        // Values containing printf-style specifiers must not throw when there are no format args.
+        assertEquals("%@", "%@".resolvableString.resolve(context))
+        assertEquals("%s", "%s".resolvableString.resolve(context))
+        assertEquals("%d", "%d".resolvableString.resolve(context))
+        assertEquals("%@ 100 %s", "%@ 100 %s".resolvableString.resolve(context))
+        assertEquals("100%", "100%".resolvableString.resolve(context))
+        assertEquals("% discount", "% discount".resolvableString.resolve(context))
+    }
+
+    @Test
+    fun `static resolvable string with format specifier still formats when args are provided`() {
+        val context = ApplicationProvider.getApplicationContext<android.content.Context>()
+        assertEquals("hello world", resolvableString(value = "hello %s", "world").resolve(context))
+        assertEquals("count: 42", resolvableString(value = "count: %d", 42).resolve(context))
+    }
+
     @Test
     fun `resolvable strings should parcelize and un-parcelize properly with raw value types`() {
         val identifierResolvable = IdentifierResolvableString(