From f7938848ed9c88c6dd590a3d79388774c37fe797 Mon Sep 17 00:00:00 2001
From: Jan Ouwens <jan.ouwens@gmail.com>
Date: Mon, 18 Feb 2019 16:24:46 +0100
Subject: [PATCH] #232: fixes NPE when verifying interfaces

---
 CHANGELOG.md                                  |  1 +
 .../equalsverifier/EqualsVerifierApi.java     |  2 +-
 .../extended_contract/InterfaceTest.java      | 20 +++++++++++++++++++
 3 files changed, 22 insertions(+), 1 deletion(-)
 create mode 100644 src/test/java/nl/jqno/equalsverifier/integration/extended_contract/InterfaceTest.java

diff --git a/CHANGELOG.md b/CHANGELOG.md
index 67fc3c0b8..92292d8b7 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -12,6 +12,7 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 
 ## [Unreleased]
 ### Fixed
+- Verifying interfaces directly causes NullPointerException. ([Issue 232](/~https://github.com/jqno/equalsverifier/issues/232))
 - Improved error messages regarding JPA's `@EmbeddedId` annotation. ([Issue 231](/~https://github.com/jqno/equalsverifier/issues/231))
 
 
diff --git a/src/main/java/nl/jqno/equalsverifier/EqualsVerifierApi.java b/src/main/java/nl/jqno/equalsverifier/EqualsVerifierApi.java
index ab714b22e..adff84fbe 100644
--- a/src/main/java/nl/jqno/equalsverifier/EqualsVerifierApi.java
+++ b/src/main/java/nl/jqno/equalsverifier/EqualsVerifierApi.java
@@ -339,7 +339,7 @@ private String buildErrorMessage(String description) {
     }
 
     private void performVerification() {
-        if (type.isEnum()) {
+        if (type.isEnum() || type.isInterface()) {
             return;
         }
 
diff --git a/src/test/java/nl/jqno/equalsverifier/integration/extended_contract/InterfaceTest.java b/src/test/java/nl/jqno/equalsverifier/integration/extended_contract/InterfaceTest.java
new file mode 100644
index 000000000..22722d59d
--- /dev/null
+++ b/src/test/java/nl/jqno/equalsverifier/integration/extended_contract/InterfaceTest.java
@@ -0,0 +1,20 @@
+package nl.jqno.equalsverifier.integration.extended_contract;
+
+import nl.jqno.equalsverifier.EqualsVerifier;
+import org.junit.Test;
+
+public class InterfaceTest {
+    @Test
+    public void succeed_whenClassIsAnInterface() {
+        EqualsVerifier.forClass(CharSequence.class)
+            .verify();
+    }
+
+    @Test
+    public void succeed_whenClassIsAnEmptyInterface() {
+        EqualsVerifier.forClass(Interface.class)
+            .verify();
+    }
+
+    interface Interface {}
+}