Fix for issue #6.

build.gradle

@@ -55,10 +55,11 @@ patchPluginXml {
     setChangeNotes("""
   <h4>V1.13 (15-Aug-22)</h4>
     <ul>
-      <li>Maintenance. Updated various dependencies (Kotlin 1.70.0) and AssertJ 3.23.1 and AssertJ-Guava 3.5.0.
+      <li>Maintenance. Updated various dependencies (Kotlin 1.7.10) and AssertJ 3.23.1 and AssertJ-Guava 3.5.0.
       <li>Tried to fix unreproducable issue #9.
       <li>Added workaround for upcoming API change in IntelliJ breaking older releases.
       <li>Added AssertThatIsZeroOne inspection demanded by issue #5.
+      <li>Fix for wrongly joining statements that cannot be trivially joined (e.g. with filteredOn). Fixes issue #6.
     </ul>
   <p>Full changelog available at <a href="https://github.com/chrisly42/cajon-plugin#changelog">Github project site</a>.</p>
 """)

src/main/java/de/platon42/intellij/plugins/cajon/CommonMatchers.kt

@@ -50,9 +50,21 @@ val MORE_EXTENSION_POINTS = CallMatcher.instanceCall(
     "singleElement", "hasOnlyOneElementSatisfying", "anyMatch", "noneMatch", "anySatisfy", "noneSatisfy"
 )!!
 
+val FILTERED_ON = CallMatcher.instanceCall(AssertJClassNames.ABSTRACT_ITERABLE_ASSERT_CLASSNAME, "filteredOn", "filteredOnNull", "filteredOnAssertions")!!
+
 val COMPLEX_CALLS_THAT_MAKES_STUFF_TRICKY = CallMatcher.anyOf(
+    EXTRACTING_CALL_MATCHERS,
     DESCRIBED_AS,
     WITH_REPRESENTATION_AND_SUCH,
+    FILTERED_ON,
+    USING_COMPARATOR,
+    IN_HEXADECIMAL_OR_BINARY
+)!!
+
+val COMPLEX_STUFF_THAT_MAKES_JOINING_IMPOSSIBLE = CallMatcher.anyOf(
+    EXTRACTING_CALL_MATCHERS,
+    WITH_REPRESENTATION_AND_SUCH,
+    FILTERED_ON,
     USING_COMPARATOR,
     IN_HEXADECIMAL_OR_BINARY
 )!!

src/main/java/de/platon42/intellij/plugins/cajon/inspections/JoinAssertThatStatementsInspection.kt

@@ -72,7 +72,7 @@ class JoinAssertThatStatementsInspection : AbstractAssertJInspection() {
                     if (!statement.hasAssertThat()) return null
 
                     val assertThatCall = PsiTreeUtil.findChildrenOfType(statement, PsiMethodCallExpression::class.java).find { ALL_ASSERT_THAT_MATCHERS.test(it) }
-                    return assertThatCall?.takeIf { it.findFluentCallTo(EXTRACTING_CALL_MATCHERS) == null }
+                    return assertThatCall?.takeIf { it.findFluentCallTo(COMPLEX_STUFF_THAT_MAKES_JOINING_IMPOSSIBLE) == null }
                 }
                 return null
             }
@@ -83,6 +83,7 @@ class JoinAssertThatStatementsInspection : AbstractAssertJInspection() {
                     val matched = when (element) {
                         is PsiUnaryExpression -> (element.operationTokenType == JavaTokenType.PLUSPLUS)
                                 || (element.operationTokenType == JavaTokenType.MINUSMINUS)
+
                         is PsiMethodCallExpression -> KNOWN_METHODS_WITH_SIDE_EFFECTS.test(element)
                         else -> false
                     }

src/test/resources/inspections/JoinStatements/JoinStatementsAfter.java

@@ -66,6 +66,9 @@ public class JoinStatements {
         assertThat(list.get(--i)).isEqualTo("foo");
         assertThat(list.get(--i)).isEqualTo("foo");
 
+        assertThat(list).filteredOn("foo", "foo").contains("narf");
+        assertThat(list).filteredOn("bar", "bar").contains("puit");
+
         org.junit.Assert.assertThat(list, null);
         fail("oh no!");
     }

src/test/resources/inspections/JoinStatements/JoinStatementsBefore.java

@@ -63,6 +63,9 @@ public class JoinStatements {
         assertThat(list.get(--i)).isEqualTo("foo");
         assertThat(list.get(--i)).isEqualTo("foo");
 
+        assertThat(list).filteredOn("foo", "foo").contains("narf");
+        assertThat(list).filteredOn("bar", "bar").contains("puit");
+
         org.junit.Assert.assertThat(list, null);
         fail("oh no!");
     }