Analysis API: add test for KtDeclaration.getReturnKtType

FE1.0 always return kotlin.Unit as return type for constructors while
FIR returns the constructed class type. I am not sure which is more
desirable. Also, I am not sure how to make FE1.0 behave the same way.

analysis/analysis-api-impl-base/tests/org/jetbrains/kotlin/analysis/api/impl/base/test/commonTestUtils.kt

@@ -12,6 +12,7 @@ import org.jetbrains.kotlin.analysis.api.KtAnalysisSession
 import org.jetbrains.kotlin.analysis.api.analyse
 import org.jetbrains.kotlin.analysis.api.symbols.KtSymbol
 import org.jetbrains.kotlin.diagnostics.PsiDiagnosticUtils.offsetToLineAndColumn
+import org.jetbrains.kotlin.psi.KtDeclaration
 import org.jetbrains.kotlin.psi.KtDeclarationWithBody
 import org.jetbrains.kotlin.psi.KtElement
 import org.jetbrains.kotlin.psi.KtNamedDeclaration
@@ -45,4 +46,8 @@ fun KtSymbol.getNameWithPositionString(): String {
 fun String.indented(indent: Int): String {
     val indentString = " ".repeat(indent)
     return indentString + replace("\n", "\n$indentString")
-}
+}
+
+fun KtDeclaration.getNameWithPositionString(): String {
+    return (presentation?.presentableText ?: name ?: this::class.simpleName) + "@" + position()
+}

analysis/analysis-api-impl-base/tests/org/jetbrains/kotlin/analysis/api/impl/base/test/components/expressionTypeProvider/AbstractDeclarationReturnTypeTest.kt

@@ -0,0 +1,41 @@
+/*
+ * Copyright 2010-2021 JetBrains s.r.o. and Kotlin Programming Language contributors.
+ * Use of this source code is governed by the Apache 2.0 license that can be found in the license/LICENSE.txt file.
+ */
+
+package org.jetbrains.kotlin.analysis.api.impl.base.test.components.expressionTypeProvider
+
+import org.jetbrains.kotlin.analysis.api.impl.barebone.test.FrontendApiTestConfiguratorService
+import org.jetbrains.kotlin.analysis.api.impl.base.test.getNameWithPositionString
+import org.jetbrains.kotlin.analysis.api.impl.base.test.test.framework.AbstractHLApiSingleFileTest
+import org.jetbrains.kotlin.psi.*
+import org.jetbrains.kotlin.test.model.TestModule
+import org.jetbrains.kotlin.test.services.TestServices
+import org.jetbrains.kotlin.test.services.assertions
+
+abstract class AbstractDeclarationReturnTypeTest(
+    configurator: FrontendApiTestConfiguratorService
+) : AbstractHLApiSingleFileTest(configurator) {
+    override fun doTestByFileStructure(ktFile: KtFile, module: TestModule, testServices: TestServices) {
+        val actual = buildString {
+            ktFile.accept(object : KtTreeVisitor<Int>() {
+                override fun visitDeclaration(dcl: KtDeclaration, data: Int): Void? {
+                    if (dcl is KtTypeParameter) return null
+                    append(" ".repeat(data))
+                    if (dcl is KtClassLikeDeclaration) {
+                        appendLine(dcl.getNameWithPositionString())
+                    } else {
+                        analyseForTest(dcl) {
+                            val returnType = dcl.getReturnKtType()
+                            append(dcl.getNameWithPositionString())
+                            append(" : ")
+                            appendLine(returnType.render())
+                        }
+                    }
+                    return super.visitDeclaration(dcl, data + 2)
+                }
+            }, 0)
+        }
+        testServices.assertions.assertEqualsToTestDataFileSibling(actual)
+    }
+}