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

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]
+    }
+  }
+}