Add a couple unit tests for StaticIpResolver and string into qa.

build-logic/tools/build.gradle.kts

@@ -18,4 +18,6 @@ ktlint {
 
 dependencies {
     implementation(libs.dnsjava)
+    testImplementation(testLibs.junit.junit)
+    testImplementation(testLibs.mockk)
 }

build-logic/tools/src/main/java/org/signal/buildtools/StaticIpResolver.kt

@@ -14,7 +14,7 @@ import kotlin.streams.toList
  * Feeds into our custom DNS resolver to provide a static IP fallback for our services.
  */
 class StaticIpResolver @JvmOverloads constructor(
-  private val resolverProvider: () -> Resolver = { SimpleResolver("1.1.1.1") }
+  private val recordFetcher: RecordFetcher = RealRecordFetcher
 ) {
 
   /**
@@ -56,13 +56,7 @@ class StaticIpResolver @JvmOverloads constructor(
 
   private fun resolveOnce(hostName: String): List<String> {
     try {
-      val resolver = resolverProvider()
-      val lookup: Lookup = doLookup(hostName)
-
-      lookup.setResolver(resolver)
-
-      val records: Array<Record>? = lookup.run()
-
+      val records = recordFetcher.fetchRecords(hostName)
       if (records != null) {
         return records
           .filter { it.type == Type.A }
@@ -71,19 +65,34 @@ class StaticIpResolver @JvmOverloads constructor(
           .map { it.hostAddress }
           .filterNotNull()
       } else {
-        throw IllegalStateException("Failed to resolve host! $hostName")
+        throw IllegalStateException("Failed to resolve host! Lookup did not return any records.. $hostName")
       }
     } catch (e: UnknownHostException) {
-      throw IllegalStateException("Failed to resolve host! $hostName")
+      throw IllegalStateException("Failed to resolve host! $hostName", e)
     }
   }
 
-  @Throws(UnknownHostException::class)
-  private fun doLookup(hostname: String): Lookup {
-    try {
-      return Lookup(hostname)
-    } catch (e: Throwable) {
-      throw UnknownHostException()
+  interface RecordFetcher {
+    fun fetchRecords(hostName: String): Array<Record>?
+  }
+
+  private object RealRecordFetcher : RecordFetcher {
+    override fun fetchRecords(hostName: String): Array<Record>? {
+      val resolver = SimpleResolver("1.1.1.1")
+      val lookup: Lookup = doLookup(hostName)
+
+      lookup.setResolver(resolver)
+
+      return lookup.run()
+    }
+
+    @Throws(UnknownHostException::class)
+    private fun doLookup(hostname: String): Lookup {
+      try {
+        return Lookup(hostname)
+      } catch (e: Throwable) {
+        throw UnknownHostException()
+      }
     }
   }
 }

build-logic/tools/src/test/java/org/signal/buildtools/StaticIpResolverTest.kt

@@ -0,0 +1,50 @@
+package org.signal.buildtools
+
+import io.mockk.every
+import io.mockk.mockk
+import org.junit.Assert.assertEquals
+import org.junit.Assert.fail
+import org.junit.Test
+import org.xbill.DNS.ARecord
+import org.xbill.DNS.DClass
+import org.xbill.DNS.Name
+import org.xbill.DNS.Record
+import java.lang.IllegalStateException
+import java.net.Inet4Address
+
+class StaticIpResolverTest {
+
+  companion object {
+    const val SIGNAL_DOT_ORG = "www.signal.org"
+    val SIGNAL_IP = byteArrayOf(123, 45, 67, 89)
+    val STRINGIFIED_IP = SIGNAL_IP.joinToString(".")
+  }
+
+  @Test
+  fun `Given a hostname with records, when I resolveToBuildConfig, then I expect a matching IP`() {
+    val staticIpResolver = StaticIpResolver(FakeRecordFetcher())
+    val actual = staticIpResolver.resolveToBuildConfig(SIGNAL_DOT_ORG)
+    val expected = """
+      new String[]{"$STRINGIFIED_IP"}
+    """.trimIndent()
+
+    assertEquals(expected, actual)
+  }
+
+  @Test(expected = IllegalStateException::class)
+  fun `Given a hostname without records, when I resolveToBuildConfig, then I expect`() {
+    val staticIpResolver = StaticIpResolver(FakeRecordFetcher(emptyMap()))
+    staticIpResolver.resolveToBuildConfig(SIGNAL_DOT_ORG)
+  }
+
+  private class FakeRecordFetcher(private val recordMap: Map<String, Array<Record>?> = mapOf(
+    SIGNAL_DOT_ORG to arrayOf(ARecord(Name.fromString("www."), DClass.ANY, 0L, mockk<Inet4Address> {
+      every { address } returns SIGNAL_IP
+      every { hostAddress } returns STRINGIFIED_IP
+    }))
+  )) : StaticIpResolver.RecordFetcher {
+    override fun fetchRecords(hostName: String): Array<Record>? {
+      return recordMap[hostName]
+    }
+  }
+}

build.gradle

@@ -64,6 +64,7 @@ task qa {
     group 'Verification'
     description 'Quality Assurance. Run before pushing.'
     dependsOn 'clean',
+            ':build-logic:tools:test',
             ':Signal-Android:testPlayProdReleaseUnitTest',
             ':Signal-Android:lintPlayProdRelease',
             'Signal-Android:ktlintCheck',