Fix a crash in DuplicateAssertion

Don't skip the first string argument on `assertEquals(String, String)`, it isn't a message.

PiperOrigin-RevId: 853249324

Author: cushon

core/src/main/java/com/google/errorprone/bugpatterns/DuplicateAssertion.java

@@ -107,10 +107,14 @@ private ImmutableSetMultimap<Assertion, Integer> extractAssertionLines(
 
   /** Returns the number of arguments to skip so we ignore {@code message} arguments. */
   private static int argumentsToSkip(MethodInvocationTree tree, VisitorState state) {
-    return ASTHelpers.isSameType(
-            getSymbol(tree).getParameters().getFirst().type, state.getSymtab().stringType, state)
-        ? 1
-        : 0;
+    var parameters = getSymbol(tree).getParameters();
+    if (!ASTHelpers.isSameType(parameters.getFirst().type, state.getSymtab().stringType, state)) {
+      return 0;
+    }
+    if (parameters.size() == 2) {
+      return 0;
+    }
+    return 1;
   }
 
   private record Assertion(String line, ConstantExpression assertee) {}

core/src/test/java/com/google/errorprone/bugpatterns/DuplicateAssertionTest.java

@@ -125,4 +125,25 @@ public void test(Iterator<Object> o) {
             """)
         .doTest();
   }
+
+  @Test
+  public void twoStringParameters() {
+    helper
+        .addSourceLines(
+            "Test.java",
+            """
+            import junit.framework.Assert;
+            import java.nio.file.Files;
+            import java.nio.file.Path;
+            import java.io.IOException;
+
+            class Test {
+              public final void checkContents(String relativePath, String expectedContents) throws IOException {
+                String actualContents = Files.readString(Path.of(relativePath));
+                Assert.assertEquals(expectedContents, actualContents);
+              }
+            }
+            """)
+        .doTest();
+  }
 }