diff --git a/formats/src/test/kotlin/com/jakewharton/diffuse/format/ClassTest.kt b/formats/src/test/kotlin/com/jakewharton/diffuse/format/ClassTest.kt
new file mode 100644
index 00000000..91ba7229
--- /dev/null
+++ b/formats/src/test/kotlin/com/jakewharton/diffuse/format/ClassTest.kt
@@ -0,0 +1,124 @@
+package com.jakewharton.diffuse.format
+
+import assertk.assertThat
+import assertk.assertions.containsOnly
+import assertk.assertions.isEqualTo
+import com.jakewharton.diffuse.format.Class.Companion.toClass
+import java.util.function.Function
+import org.junit.Test
+
+@Suppress("SpellCheckingInspection") // Suppress `Lcom/**` warnings in type descriptors.
+class ClassTest {
+  @Test
+  fun testClassParsing() {
+    val input = this::class.java.requireResource($$"ClassTest$Dummy.class").asInput()
+    val clazz = input.toClass()
+    val type = TypeDescriptor($$"Lcom/jakewharton/diffuse/format/ClassTest$Dummy;")
+
+    assertThat(clazz.descriptor).isEqualTo(type)
+
+    val initMethod = Method(type, "<init>", emptyList(), TypeDescriptor("V"))
+    val stringArrayDescriptor = TypeDescriptor("[Ljava/lang/String;")
+    val getStringArrayMethod = Method(type, "getStringArray", emptyList(), stringArrayDescriptor)
+    val setStringArrayMethod =
+      Method(type, "setStringArray", listOf(stringArrayDescriptor), TypeDescriptor("V"))
+    val useArrayMethod = Method(type, "useArray", emptyList(), TypeDescriptor("V"))
+    val useLambdaMethod = Method(type, "useLambda", emptyList(), TypeDescriptor("V"))
+    val lambdaMethod =
+      Method(
+        type,
+        $$"useLambda$lambda$0",
+        listOf(TypeDescriptor("Ljava/lang/String;")),
+        TypeDescriptor("Ljava/lang/String;"),
+      )
+    val stringArrayField = Field(type, "stringArray", stringArrayDescriptor)
+
+    assertThat(clazz.declaredMembers)
+      .containsOnly(
+        initMethod,
+        getStringArrayMethod,
+        setStringArrayMethod,
+        useArrayMethod,
+        useLambdaMethod,
+        lambdaMethod,
+        stringArrayField,
+      )
+
+    val objType = TypeDescriptor("Ljava/lang/Object;")
+    val objInit = Method(objType, "<init>", emptyList(), TypeDescriptor("V"))
+    val objClone = Method(objType, "clone", emptyList(), objType)
+    val objToString = Method(objType, "toString", emptyList(), TypeDescriptor("Ljava/lang/String;"))
+    val lambdaMetafactoryMethod =
+      Method(
+        TypeDescriptor("Ljava/lang/invoke/LambdaMetafactory;"),
+        "metafactory",
+        listOf(
+          TypeDescriptor($$"Ljava/lang/invoke/MethodHandles$Lookup;"),
+          TypeDescriptor("Ljava/lang/String;"),
+          TypeDescriptor("Ljava/lang/invoke/MethodType;"),
+          TypeDescriptor("Ljava/lang/invoke/MethodType;"),
+          TypeDescriptor("Ljava/lang/invoke/MethodHandle;"),
+          TypeDescriptor("Ljava/lang/invoke/MethodType;"),
+        ),
+        TypeDescriptor("Ljava/lang/invoke/CallSite;"),
+      )
+    val functionApply =
+      Method(TypeDescriptor("Ljava/util/function/Function;"), "apply", listOf(objType), objType)
+    val intrinsicsType = TypeDescriptor("Lkotlin/jvm/internal/Intrinsics;")
+    val intrinsicsCheckNotNull =
+      Method(intrinsicsType, "checkNotNull", listOf(objType), TypeDescriptor("V"))
+    val intrinsicsCheckNotNullParameter =
+      Method(
+        intrinsicsType,
+        "checkNotNullParameter",
+        listOf(objType, TypeDescriptor("Ljava/lang/String;")),
+        TypeDescriptor("V"),
+      )
+    val stringsKtType = TypeDescriptor("Lkotlin/text/StringsKt;")
+    val trimMethod =
+      Method(
+        stringsKtType,
+        "trim",
+        listOf(TypeDescriptor("Ljava/lang/CharSequence;")),
+        TypeDescriptor("Ljava/lang/CharSequence;"),
+      )
+    val arrayToString =
+      Method(
+        TypeDescriptor("[Ljava/lang/Object;"),
+        "toString",
+        emptyList(),
+        TypeDescriptor("Ljava/lang/String;"),
+      )
+
+    assertThat(clazz.referencedMembers)
+      .containsOnly(
+        lambdaMethod,
+        stringArrayField,
+        objInit,
+        objClone,
+        objToString,
+        lambdaMetafactoryMethod,
+        functionApply,
+        intrinsicsCheckNotNull,
+        intrinsicsCheckNotNullParameter,
+        trimMethod,
+        arrayToString,
+      )
+  }
+
+  @Suppress("unused") // Used for parsing.
+  class Dummy {
+    var stringArray: Array<String> = emptyArray()
+
+    fun useArray() {
+      val arr = stringArray
+      arr.toString()
+      arr.clone()
+    }
+
+    fun useLambda() {
+      val func = Function<String, String> { it.trim() }
+      func.apply(" useLambda ")
+    }
+  }
+}
diff --git a/formats/src/test/kotlin/com/jakewharton/diffuse/format/ResourceInput.kt b/formats/src/test/kotlin/com/jakewharton/diffuse/format/ResourceInput.kt
index bc1b3a23..581429a7 100644
--- a/formats/src/test/kotlin/com/jakewharton/diffuse/format/ResourceInput.kt
+++ b/formats/src/test/kotlin/com/jakewharton/diffuse/format/ResourceInput.kt
@@ -1,12 +1,17 @@
 package com.jakewharton.diffuse.format
 
 import com.jakewharton.diffuse.io.Input
+import java.lang.Class
 import java.net.URL
 import okio.buffer
 import okio.source
 
 fun URL.asInput(): Input = ResourceInput(this)
 
+fun Class<*>.requireResource(name: String): URL {
+  return checkNotNull(getResource(name)) { "Resource $name not found." }
+}
+
 private class ResourceInput(private val url: URL) : Input {
   override val name
     get() = url.path.substringAfterLast('/')