[java-highlighting] Refactor FunctionalInterfaceTest to avoid internals dependency; move completion stuff out of LambdaHighlightingUtil

Part of IDEA-365344 Create a new Java error highlighter with minimal dependencies (PSI only)

GitOrigin-RevId: 4bd5447dd5fc2342f5e9b23e693f7683594470f5

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/AbstractClass.java

@@ -1 +1,2 @@
+<error descr="Foo is not a functional interface">@FunctionalInterface</error>
 abstract class Foo { public abstract void run(); }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/Clone.java

@@ -1,3 +1,4 @@
+<error descr="Multiple non-overriding abstract methods found in Foo">@FunctionalInterface</error>
 interface Foo {
   int m();
   Object clone();

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/IntersectionOf2FunctionalTypesWithEqualAfterSubstitutionSignatures.java

@@ -8,6 +8,6 @@ interface Y<T> {
 
 class Test {
   {
-    ((X & <caret>Y<Integer>) (x) -> {}).m(1);
+    ((X & Y<Integer>) <error descr="Multiple non-overriding abstract methods found in X & Y<Integer>">(x) -> {}</error>).m<error descr="Ambiguous method call: both 'X.m(Integer)' and 'Y.m(Integer)' match">(1)</error>;
   }
 }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/MethodWithTypeParam.java

@@ -1,3 +1,8 @@
+@FunctionalInterface
 interface Foo { <T> T execute(Action<T> a); }
 interface Action<A>{}
-  // Functional
+
+class Use {
+  // Functional but not lambda-compatible
+  Foo foo = <error descr="Target method is generic">a -> null</error>;
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/MultipleMethods.java

@@ -1,3 +1,4 @@
 interface Bar { boolean equals(Object obj); }
 
+@FunctionalInterface
 interface Foo extends Bar { int compare(String o1, String o2); }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/MultipleMethodsInOne.java

@@ -1,3 +1,4 @@
+@FunctionalInterface
 interface Foo<T> {
  boolean equals(Object obj);
  int compare(T o1, T o2);

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/NoMethods.java

@@ -1 +1,2 @@
+<error descr="No target method found">@FunctionalInterface</error>
 interface Foo { boolean equals(Object obj); }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/Simple.java

@@ -1 +1,2 @@
+@FunctionalInterface
 interface Foo { void run(); }

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/TwoMethodsNoSubSignature.java

@@ -1,4 +1,5 @@
 interface X { int m(Iterable<String> arg); }
 interface Y { int m(Iterable<Integer> arg); }
+<error descr="Multiple non-overriding abstract methods found in Foo">@FunctionalInterface</error>
 interface Foo extends X, Y {}
   // Not functional: No method has a subsignature of all abstract methods

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/TwoMethodsNoSubSignature1.java

@@ -1,4 +1,5 @@
 interface X { int m(Iterable<String> arg, Class c); }
 interface Y { int m(Iterable arg, Class<?> c); }
+<error descr="Multiple non-overriding abstract methods found in Foo">@FunctionalInterface</error>
 interface Foo extends X, Y {}
   // Not functional: No method has a subsignature of all abstract methods

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/TwoMethodsSameSignature.java

@@ -1,4 +1,5 @@
 import java.util.*;
 interface X { int m(Iterable<String> arg); }
 interface Y { int m(Iterable<String> arg); }
+@FunctionalInterface
 interface Foo extends X, Y {}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/TwoMethodsSameSignatureTypeParams.java

@@ -1,5 +1,11 @@
 interface Action<A>{}
 interface X { <T> T execute(Action<T> a); }
 interface Y { <S> S execute(Action<S> a); }
+@FunctionalInterface
 interface Foo extends X, Y {}
-  // Functional: signatures are "the same"
+
+class Use {
+  // Functional: signatures are "the same"
+  // but not lambda-compatible
+  Foo foo = <error descr="Target method is generic">a -> null</error>;
+}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/TwoMethodsSameSubstSignature.java

@@ -2,4 +2,5 @@ interface Foo1<T, N extends Number> {
   void m(T arg);
   void m(N arg);
 }
+@FunctionalInterface
 interface Foo extends Foo1<Integer, Integer> {}

java/java-tests/testData/codeInsight/daemonCodeAnalyzer/lambda/functionalInterface/TwoMethodsSubSignature.java

@@ -1,4 +1,5 @@
 import java.util.*;
 interface X { Iterable m(Iterable<String> arg); }
 interface Y { Iterable<String> m(Iterable arg); }
+@FunctionalInterface
 interface Foo extends X, Y {}