provide accurate completions when triggered from the middle of an instance method

Author: Matthew McGarvey

src/main/kotlin/org/javacs/kt/completion/Completions.kt

@@ -104,6 +104,8 @@ private fun completableElement(file: CompiledFile, cursor: Int): KtElement? {
             el as? KtQualifiedExpression ?: el.parent as? KtQualifiedExpression ?:
             // something::?
             el as? KtCallableReferenceExpression ?: el.parent as? KtCallableReferenceExpression ?:
+            // something.foo() with cursor in the method
+            el.parent?.parent as? KtQualifiedExpression ?:
             // ?
             el as? KtNameReferenceExpression
 }

src/test/kotlin/org/javacs/kt/CompletionsTest.kt

@@ -56,6 +56,13 @@ class InstanceMemberTest : SingleFileTestFixture("completions", "InstanceMember.
         assertThat(labels, hasItem(startsWith("findFunctionReference")))
         assertThat(labels, not(hasItem("instanceFoo")))
     }
+
+    @Test fun `find completions on letters of method call`() {
+        val completions = languageServer.textDocumentService.completion(completionParams(file, 26, 26)).get().right!!
+        val labels = completions.items.map { it.label }
+
+        assertThat(labels, hasItems(startsWith("instanceFee"), startsWith("instanceFoo")))
+    }
 }
 
 class InstanceMembersJava : SingleFileTestFixture("completions", "InstanceMembersJava.kt") {

src/test/resources/completions/InstanceMember.kt

@@ -22,10 +22,15 @@ private fun completeIdentifierInsideCall() {
     instance.instanceFoo(f)
 }
 
+private fun findCompletionsForLettersInFullMethod() {
+    SomeClass().instanceFoo()
+}
+
 private class SomeClass {
     fun instanceFoo() = "Foo"
+    fun instanceFee() = "Fee"
     private fun privateInstanceFoo() = "Foo"
     var fooVar = 1
 }
 
-private fun SomeClass.extensionFoo() = "Bar"
+private fun SomeClass.extensionFoo() = "Bar"