Adds tests for FieldMutator

equalsverifier-core/src/test/java/nl/jqno/equalsverifier/internal/reflection/FieldMutatorTest.java

@@ -0,0 +1,65 @@
+package nl.jqno.equalsverifier.internal.reflection;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+import org.junit.jupiter.api.Test;
+
+public class FieldMutatorTest {
+
+    private FieldProbe p;
+    private FieldMutator sut;
+    private Container o = new Container();
+
+    @Test
+    public void setPrimitive() throws NoSuchFieldException {
+        p = FieldProbe.of(Container.class.getDeclaredField("i"));
+        sut = new FieldMutator(p);
+
+        assertEquals(10, o.i);
+        sut.setNewValue(o, 1337);
+        assertEquals(1337, o.i);
+    }
+
+    @Test
+    public void setObject() throws NoSuchFieldException {
+        p = FieldProbe.of(Container.class.getDeclaredField("s"));
+        sut = new FieldMutator(p);
+
+        assertEquals("NON-FINAL", o.s);
+        sut.setNewValue(o, "changed");
+        assertEquals("changed", o.s);
+    }
+
+    @Test
+    public void dontSetConstantPrimitive() throws NoSuchFieldException {
+        p = FieldProbe.of(Container.class.getDeclaredField("FINAL_INT"));
+        sut = new FieldMutator(p);
+
+        assertEquals(42, Container.FINAL_INT);
+        sut.setNewValue(o, 1337);
+        assertEquals(42, Container.FINAL_INT);
+    }
+
+    @Test
+    public void dontSetConstantObject() throws NoSuchFieldException {
+        p = FieldProbe.of(Container.class.getDeclaredField("FINAL_STRING"));
+        sut = new FieldMutator(p);
+
+        assertEquals("FINAL", Container.FINAL_STRING);
+        sut.setNewValue(o, "changed");
+        assertEquals("FINAL", Container.FINAL_STRING);
+    }
+
+    static class Container {
+
+        private static final int FINAL_INT = 42;
+        private static final String FINAL_STRING = "FINAL";
+        private final int i;
+        private final String s;
+
+        public Container() {
+            this.i = 10;
+            this.s = "NON-FINAL";
+        }
+    }
+}