review fixes + add tests

presentation-compiler/src/main/dotty/tools/pc/SymbolInformationProvider.scala

@@ -14,18 +14,13 @@ import dotty.tools.dotc.core.StdNames.nme
 import dotty.tools.dotc.core.Symbols.*
 import dotty.tools.pc.utils.MtagsEnrichments.metalsDealias
 import dotty.tools.pc.SemanticdbSymbols
+import dotty.tools.pc.utils.MtagsEnrichments.allSymbols
 
 class SymbolInformationProvider(using Context):
   private def toSymbols(
       pkg: String,
       parts: List[(String, Boolean)],
   ): List[Symbol] =
-    def collectSymbols(denotation: Denotation): List[Symbol] =
-      denotation match
-        case MultiDenotation(denot1, denot2) =>
-          collectSymbols(denot1) ++ collectSymbols(denot2)
-        case denot => List(denot.symbol)
-
     def loop(
         owners: List[Symbol],
         parts: List[(String, Boolean)],
@@ -37,7 +32,7 @@ class SymbolInformationProvider(using Context):
               val next =
                 if isClass then owner.info.member(typeName(head))
                 else owner.info.member(termName(head))
-              collectSymbols(next).filter(_.exists)
+              next.allSymbols
             }
           if foundSymbols.nonEmpty then loop(foundSymbols, tl)
           else Nil
@@ -70,9 +65,8 @@ class SymbolInformationProvider(using Context):
       catch case NonFatal(e) => Nil
 
     val (searchedSymbol, alternativeSymbols) =
-      foundSymbols.partition(compilerSymbol =>
+      foundSymbols.partition: compilerSymbol =>
         SemanticdbSymbols.symbolName(compilerSymbol) == symbol
-      )
 
     searchedSymbol match
       case Nil => None

presentation-compiler/test/dotty/tools/pc/tests/info/InfoSuite.scala

@@ -0,0 +1,56 @@
+package dotty.tools.pc.tests.info
+
+import scala.meta.internal.jdk.CollectionConverters._
+import scala.meta.pc.PcSymbolKind
+import scala.meta.pc.PcSymbolProperty
+
+import scala.meta.pc.PcSymbolInformation
+import dotty.tools.pc.base.BasePCSuite
+import scala.language.unsafeNulls
+import org.junit.Test
+
+class InfoSuite extends BasePCSuite {
+
+  def getInfo(symbol: String): PcSymbolInformation = {
+    val result = presentationCompiler.info(symbol).get()
+    assertEquals(true, result.isPresent(), s"no info returned for symbol $symbol")
+    assertNoDiff(result.get().symbol(), symbol)
+    result.get()
+  }
+
+  @Test def `list` =
+    val info = getInfo("scala/collection/immutable/List#")
+    assertEquals(true, info.properties().contains(PcSymbolProperty.ABSTRACT), s"class List should be abstract")
+    assertEquals(
+      true,
+      info.parents().contains("scala/collection/immutable/LinearSeq#"),
+      "class List should extend LinearSeq"
+    )
+
+  @Test def `empty-list-constructor` =
+    val info = getInfo("scala/collection/immutable/List.empty().")
+    assertNoDiff(info.classOwner(), "scala/collection/immutable/List.")
+    assertEquals(info.kind(), PcSymbolKind.METHOD, "List.empty() should be a method")
+
+  @Test def `assert` =
+    val info = getInfo("scala/Predef.assert().")
+    assertEquals(info.kind(), PcSymbolKind.METHOD, "assert() should be a method")
+    assertNoDiff(info.classOwner(), "scala/Predef.")
+    assertEquals(
+      info.alternativeSymbols().asScala.mkString("\n"),
+      "scala/Predef.assert(+1).",
+      "there should be a single alternative symbol to assert()"
+    )
+
+  @Test def `flatMap` =
+    val info = getInfo("scala/collection/immutable/List#flatMap().")
+    assertEquals(info.kind(), PcSymbolKind.METHOD, "List.flatMap() should be a method")
+    assertNoDiff(info.classOwner(), "scala/collection/immutable/List#")
+    assertNoDiff(
+      info.overriddenSymbols().asScala.mkString("\n"),
+      """|scala/collection/StrictOptimizedIterableOps#flatMap().
+         |scala/collection/IterableOps#flatMap().
+         |scala/collection/IterableOnceOps#flatMap().
+         |""".stripMargin
+    )
+}