diff --git a/src/main/kotlin/texlab/TextDocumentServiceImpl.kt b/src/main/kotlin/texlab/TextDocumentServiceImpl.kt
index 09b7e3e8..cd9878c2 100644
--- a/src/main/kotlin/texlab/TextDocumentServiceImpl.kt
+++ b/src/main/kotlin/texlab/TextDocumentServiceImpl.kt
@@ -165,8 +165,8 @@ class TextDocumentServiceImpl(val workspaceActor: WorkspaceActor) : CustomTextDo
                     LatexCitationSymbolProvider,
                     BibtexEntrySymbolProvider)
 
-    private val renameProvider: FeatureProvider<RenameParams, List<WorkspaceEdit>> =
-            FeatureProvider.concat(
+    private val renameProvider: FeatureProvider<RenameParams, WorkspaceEdit?> =
+            FeatureProvider.choice(
                     LatexCommandRenamer,
                     LatexEnvironmentRenamer,
                     LatexLabelRenamer,
@@ -189,14 +189,14 @@ class TextDocumentServiceImpl(val workspaceActor: WorkspaceActor) : CustomTextDo
     private val highlightProvider: FeatureProvider<TextDocumentPositionParams, List<DocumentHighlight>> =
             FeatureProvider.concat(LatexLabelHighlightProvider)
 
-    private val hoverProvider: FeatureProvider<TextDocumentPositionParams, List<Hover>> =
-            FeatureProvider.concat(
+    private val hoverProvider: FeatureProvider<TextDocumentPositionParams, Hover?> =
+            FeatureProvider.choice(
                     LatexComponentHoverProvider,
                     LatexCitationHoverProvider,
                     LatexMathEnvironmentHoverProvider,
                     LatexMathEquationHoverProvider,
                     LatexMathInlineHoverProvider,
-                    DeferredProvider(::LatexCommandHoverProvider, componentDatabase, emptyList()),
+                    DeferredProvider(::LatexCommandHoverProvider, componentDatabase, null),
                     BibtexEntryTypeHoverProvider,
                     BibtexFieldHoverProvider)
 
@@ -290,7 +290,7 @@ class TextDocumentServiceImpl(val workspaceActor: WorkspaceActor) : CustomTextDo
     }
 
     override fun rename(params: RenameParams): CompletableFuture<WorkspaceEdit?> = future {
-        runFeature(renameProvider, params.textDocument, params).firstOrNull()
+        runFeature(renameProvider, params.textDocument, params)
     }
 
     override fun documentLink(params: DocumentLinkParams)
@@ -351,7 +351,7 @@ class TextDocumentServiceImpl(val workspaceActor: WorkspaceActor) : CustomTextDo
 
     override fun hover(params: TextDocumentPositionParams)
             : CompletableFuture<Hover?> = future {
-        runFeature(hoverProvider, params.textDocument, params).firstOrNull()
+        runFeature(hoverProvider, params.textDocument, params)
     }
 
     override fun formatting(params: DocumentFormattingParams)
@@ -432,9 +432,9 @@ class TextDocumentServiceImpl(val workspaceActor: WorkspaceActor) : CustomTextDo
         }
     }
 
-    private suspend fun <T, R> runFeature(provider: FeatureProvider<T, List<R>>,
+    private suspend fun <T, R> runFeature(provider: FeatureProvider<T, R>,
                                           document: TextDocumentIdentifier,
-                                          params: T): List<R> {
+                                          params: T): R {
         return workspaceActor.withWorkspace { workspace ->
             val uri = URIHelper.parse(document.uri)
             val request = FeatureRequest(uri, workspace, params, logger)
diff --git a/src/main/kotlin/texlab/hover/BibtexEntryTypeHoverProvider.kt b/src/main/kotlin/texlab/hover/BibtexEntryTypeHoverProvider.kt
index d4d529b6..90feace4 100644
--- a/src/main/kotlin/texlab/hover/BibtexEntryTypeHoverProvider.kt
+++ b/src/main/kotlin/texlab/hover/BibtexEntryTypeHoverProvider.kt
@@ -9,21 +9,20 @@ import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 import texlab.syntax.bibtex.BibtexEntrySyntax
 
-object BibtexEntryTypeHoverProvider : FeatureProvider<TextDocumentPositionParams, List<Hover>> {
-    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): List<Hover> {
+object BibtexEntryTypeHoverProvider : FeatureProvider<TextDocumentPositionParams, Hover?> {
+    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): Hover? {
         if (request.document !is BibtexDocument) {
-            return emptyList()
+            return null
         }
 
         val name = request.document.tree.root.children
                 .filterIsInstance<BibtexEntrySyntax>()
                 .firstOrNull { it.type.range.contains(request.params.position) }
                 ?.type?.text?.substring(1)?.toLowerCase()
-                ?: return emptyList()
+                ?: return null
 
         val metadata = BibtexEntryTypeMetadataProvider.getMetadata(name)
-        val documentation = metadata?.documentation ?: return emptyList()
-        return listOf(Hover(documentation))
-
+        val documentation = metadata?.documentation ?: return null
+        return Hover(documentation)
     }
 }
diff --git a/src/main/kotlin/texlab/hover/BibtexFieldHoverProvider.kt b/src/main/kotlin/texlab/hover/BibtexFieldHoverProvider.kt
index ccc7526b..104f8aac 100644
--- a/src/main/kotlin/texlab/hover/BibtexFieldHoverProvider.kt
+++ b/src/main/kotlin/texlab/hover/BibtexFieldHoverProvider.kt
@@ -11,22 +11,22 @@ import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 import texlab.syntax.bibtex.BibtexFieldSyntax
 
-object BibtexFieldHoverProvider : FeatureProvider<TextDocumentPositionParams, List<Hover>> {
-    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): List<Hover> {
+object BibtexFieldHoverProvider : FeatureProvider<TextDocumentPositionParams, Hover?> {
+    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): Hover? {
         if (request.document !is BibtexDocument) {
-            return emptyList()
+            return null
         }
 
         val fieldNode = request.document.tree.root.descendants()
                 .filterIsInstance<BibtexFieldSyntax>()
                 .firstOrNull { it.name.range.contains(request.params.position) }
-                ?: return emptyList()
+                ?: return null
 
-        val fieldName = BibtexField.parse(fieldNode.name.text) ?: return emptyList()
+        val fieldName = BibtexField.parse(fieldNode.name.text) ?: return null
         val markup = MarkupContent().apply {
             kind = MarkupKind.MARKDOWN
             value = fieldName.documentation()
         }
-        return listOf(Hover(markup))
+        return Hover(markup)
     }
 }
diff --git a/src/main/kotlin/texlab/hover/LatexCitationHoverProvider.kt b/src/main/kotlin/texlab/hover/LatexCitationHoverProvider.kt
index a8b29e13..e6de30cd 100644
--- a/src/main/kotlin/texlab/hover/LatexCitationHoverProvider.kt
+++ b/src/main/kotlin/texlab/hover/LatexCitationHoverProvider.kt
@@ -15,23 +15,21 @@ import texlab.provider.FeatureRequest
 import texlab.syntax.bibtex.BibtexEntrySyntax
 
 @ObsoleteCoroutinesApi
-object LatexCitationHoverProvider : FeatureProvider<TextDocumentPositionParams, List<Hover>> {
-    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): List<Hover> {
-        val key = getKey(request) ?: return emptyList()
-
+object LatexCitationHoverProvider : FeatureProvider<TextDocumentPositionParams, Hover?> {
+    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): Hover? {
+        val key = getKey(request) ?: return null
         val entry = request.relatedDocuments
                 .filterIsInstance<BibtexDocument>()
                 .flatMap { it.tree.root.children.filterIsInstance<BibtexEntrySyntax>() }
                 .firstOrNull { it.name?.text == key }
-                ?: return emptyList()
+                ?: return null
 
         val formatter = BibtexFormatter(insertSpaces = true, tabSize = 4, lineLength = -1)
-        val hover = Hover(MarkupContent().apply {
+        val markup = MarkupContent().apply {
             kind = MarkupKind.MARKDOWN
             value = BibtexCitationActor.cite(formatter.format(entry))
-        })
-
-        return listOf(hover)
+        }
+        return Hover(markup)
     }
 
     private fun getKey(request: FeatureRequest<TextDocumentPositionParams>): String? {
diff --git a/src/main/kotlin/texlab/hover/LatexCommandHoverProvider.kt b/src/main/kotlin/texlab/hover/LatexCommandHoverProvider.kt
index 986ad128..ac2106a8 100644
--- a/src/main/kotlin/texlab/hover/LatexCommandHoverProvider.kt
+++ b/src/main/kotlin/texlab/hover/LatexCommandHoverProvider.kt
@@ -12,26 +12,27 @@ import texlab.provider.FeatureRequest
 import texlab.syntax.latex.LatexCommandSyntax
 
 class LatexCommandHoverProvider(private val database: LatexComponentSource) :
-        FeatureProvider<TextDocumentPositionParams, List<Hover>> {
-    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): List<Hover> {
+        FeatureProvider<TextDocumentPositionParams, Hover?> {
+    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): Hover? {
         if (request.document !is LatexDocument) {
-            return emptyList()
+            return null
         }
 
         val command = request.document.tree.root
                 .descendants()
                 .filterIsInstance<LatexCommandSyntax>()
                 .firstOrNull { it.name.range.contains(request.params.position) }
-                ?: return emptyList()
+                ?: return null
 
         val components = database.getRelatedComponents(request.relatedDocuments)
                 .filter { it.commands.contains(command.name.text.substring(1)) }
                 .flatMap { it.fileNames }
 
         val separator = System.lineSeparator().repeat(2)
-        return listOf(Hover(MarkupContent().apply {
+        val markup = MarkupContent().apply {
             kind = MarkupKind.MARKDOWN
             value = components.joinToString(separator)
-        }))
+        }
+        return Hover(markup)
     }
 }
diff --git a/src/main/kotlin/texlab/hover/LatexComponentHoverProvider.kt b/src/main/kotlin/texlab/hover/LatexComponentHoverProvider.kt
index 927b20c0..ac643c85 100644
--- a/src/main/kotlin/texlab/hover/LatexComponentHoverProvider.kt
+++ b/src/main/kotlin/texlab/hover/LatexComponentHoverProvider.kt
@@ -8,19 +8,19 @@ import texlab.metadata.LatexComponentMetadataProvider
 import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 
-object LatexComponentHoverProvider : FeatureProvider<TextDocumentPositionParams, List<Hover>> {
-    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): List<Hover> {
+object LatexComponentHoverProvider : FeatureProvider<TextDocumentPositionParams, Hover?> {
+    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): Hover? {
         if (request.document !is LatexDocument) {
-            return emptyList()
+            return null
         }
 
         val name = request.document.tree.includes
                 .filter { it.isUnitImport }
                 .firstOrNull { it.command.range.contains(request.params.position) }
-                ?.path ?: return emptyList()
+                ?.path ?: return null
 
         val metadata = LatexComponentMetadataProvider.getMetadata(name)
-        val documentation = metadata?.documentation ?: return emptyList()
-        return listOf(Hover(documentation))
+        val documentation = metadata?.documentation ?: return null
+        return Hover(documentation)
     }
 }
diff --git a/src/main/kotlin/texlab/hover/LatexMathHoverProvider.kt b/src/main/kotlin/texlab/hover/LatexMathHoverProvider.kt
index f09d74ff..3c1b92e7 100644
--- a/src/main/kotlin/texlab/hover/LatexMathHoverProvider.kt
+++ b/src/main/kotlin/texlab/hover/LatexMathHoverProvider.kt
@@ -9,16 +9,16 @@ import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 
 
-abstract class LatexMathHoverProvider : FeatureProvider<TextDocumentPositionParams, List<Hover>> {
-    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): List<Hover> {
+abstract class LatexMathHoverProvider : FeatureProvider<TextDocumentPositionParams, Hover?> {
+    override suspend fun get(request: FeatureRequest<TextDocumentPositionParams>): Hover? {
         if (request.document !is LatexDocument) {
-            return emptyList()
+            return null
         }
 
-        val range = getCodeRange(request.document, request.params.position) ?: return emptyList()
+        val range = getCodeRange(request.document, request.params.position) ?: return null
         val code = request.document.tree.extract(range)
-        val icon = LatexFormulaRenderer.render(code) ?: return emptyList()
-        return listOf(Hover(icon))
+        val icon = LatexFormulaRenderer.render(code) ?: return null
+        return Hover(icon)
     }
 
     protected abstract fun getCodeRange(document: LatexDocument, position: Position): Range?
diff --git a/src/main/kotlin/texlab/provider/FeatureProvider.kt b/src/main/kotlin/texlab/provider/FeatureProvider.kt
index 646028ed..0b9db72d 100644
--- a/src/main/kotlin/texlab/provider/FeatureProvider.kt
+++ b/src/main/kotlin/texlab/provider/FeatureProvider.kt
@@ -21,5 +21,18 @@ interface FeatureProvider<T, R> {
                 providers.flatMap { it.get(request) }
             }
         }
+
+        fun <T, R> choice(vararg providers: FeatureProvider<T, R?>): FeatureProvider<T, R?> {
+            return create { request ->
+                for (provider in providers) {
+                    val result = provider.get(request)
+                    if (result != null) {
+                        return@create result
+                    }
+                }
+
+                null
+            }
+        }
     }
 }
diff --git a/src/main/kotlin/texlab/rename/BibtexEntryRenamer.kt b/src/main/kotlin/texlab/rename/BibtexEntryRenamer.kt
index 2000e902..36216cc1 100644
--- a/src/main/kotlin/texlab/rename/BibtexEntryRenamer.kt
+++ b/src/main/kotlin/texlab/rename/BibtexEntryRenamer.kt
@@ -12,12 +12,12 @@ import texlab.provider.FeatureRequest
 import texlab.syntax.Token
 import texlab.syntax.bibtex.BibtexEntrySyntax
 
-object BibtexEntryRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>> {
-    override suspend fun get(request: FeatureRequest<RenameParams>): List<WorkspaceEdit> {
+object BibtexEntryRenamer : FeatureProvider<RenameParams, WorkspaceEdit?> {
+    override suspend fun get(request: FeatureRequest<RenameParams>): WorkspaceEdit? {
         val token = when (request.document) {
             is BibtexDocument -> findEntry(request.document, request.params.position)
             is LatexDocument -> findCitation(request.document, request.params.position)
-        } ?: return emptyList()
+        } ?: return null
 
         val changes = mutableMapOf<String, List<TextEdit>>()
         for (document in request.relatedDocuments) {
@@ -39,7 +39,7 @@ object BibtexEntryRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>> {
             changes[document.uri.toString()] = edits
         }
 
-        return listOf(WorkspaceEdit(changes))
+        return WorkspaceEdit(changes)
     }
 
     private fun findEntry(document: BibtexDocument, position: Position): Token? {
diff --git a/src/main/kotlin/texlab/rename/LatexCommandRenamer.kt b/src/main/kotlin/texlab/rename/LatexCommandRenamer.kt
index 21340fae..689776b1 100644
--- a/src/main/kotlin/texlab/rename/LatexCommandRenamer.kt
+++ b/src/main/kotlin/texlab/rename/LatexCommandRenamer.kt
@@ -9,16 +9,16 @@ import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 import texlab.syntax.latex.LatexCommandSyntax
 
-object LatexCommandRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>> {
-    override suspend fun get(request: FeatureRequest<RenameParams>): List<WorkspaceEdit> {
+object LatexCommandRenamer : FeatureProvider<RenameParams, WorkspaceEdit?> {
+    override suspend fun get(request: FeatureRequest<RenameParams>): WorkspaceEdit? {
         if (request.document !is LatexDocument) {
-            return emptyList()
+            return null
         }
 
         val command = request.document.tree.root
                 .descendants()
                 .filterIsInstance<LatexCommandSyntax>()
-                .firstOrNull { it.name.range.contains(request.params.position) } ?: return emptyList()
+                .firstOrNull { it.name.range.contains(request.params.position) } ?: return null
 
         val changes = mutableMapOf<String, List<TextEdit>>()
         for (document in request.relatedDocuments.filterIsInstance<LatexDocument>()) {
@@ -29,6 +29,6 @@ object LatexCommandRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>>
             changes[document.uri.toString()] = edits
         }
 
-        return listOf(WorkspaceEdit(changes))
+        return WorkspaceEdit(changes)
     }
 }
diff --git a/src/main/kotlin/texlab/rename/LatexEnvironmentRenamer.kt b/src/main/kotlin/texlab/rename/LatexEnvironmentRenamer.kt
index d956f0f2..8ad93bdc 100644
--- a/src/main/kotlin/texlab/rename/LatexEnvironmentRenamer.kt
+++ b/src/main/kotlin/texlab/rename/LatexEnvironmentRenamer.kt
@@ -8,10 +8,10 @@ import texlab.contains
 import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 
-object LatexEnvironmentRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>> {
-    override suspend fun get(request: FeatureRequest<RenameParams>): List<WorkspaceEdit> {
+object LatexEnvironmentRenamer : FeatureProvider<RenameParams, WorkspaceEdit?> {
+    override suspend fun get(request: FeatureRequest<RenameParams>): WorkspaceEdit? {
         if (request.document !is LatexDocument) {
-            return emptyList()
+            return null
         }
 
         for (environment in request.document.tree.environments) {
@@ -21,10 +21,10 @@ object LatexEnvironmentRenamer : FeatureProvider<RenameParams, List<WorkspaceEdi
                 val edits = listOf(
                         TextEdit(environment.beginNameRange, request.params.newName),
                         TextEdit(environment.endNameRange, request.params.newName))
-                return listOf(WorkspaceEdit(mutableMapOf(request.uri.toString() to edits)))
+                return WorkspaceEdit(mapOf(request.uri.toString() to edits))
             }
         }
 
-        return emptyList()
+        return null
     }
 }
diff --git a/src/main/kotlin/texlab/rename/LatexLabelRenamer.kt b/src/main/kotlin/texlab/rename/LatexLabelRenamer.kt
index 064b9cce..4a14e40f 100644
--- a/src/main/kotlin/texlab/rename/LatexLabelRenamer.kt
+++ b/src/main/kotlin/texlab/rename/LatexLabelRenamer.kt
@@ -8,17 +8,17 @@ import texlab.contains
 import texlab.provider.FeatureProvider
 import texlab.provider.FeatureRequest
 
-object LatexLabelRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>> {
-    override suspend fun get(request: FeatureRequest<RenameParams>): List<WorkspaceEdit> {
+object LatexLabelRenamer : FeatureProvider<RenameParams, WorkspaceEdit?> {
+    override suspend fun get(request: FeatureRequest<RenameParams>): WorkspaceEdit? {
         if (request.document !is LatexDocument) {
-            return emptyList()
+            return null
         }
 
         val label = request.document.tree
                 .labelReferences
                 .plus(request.document.tree.labelDefinitions)
                 .firstOrNull { it.name.range.contains(request.params.position) }
-                ?: return emptyList()
+                ?: return null
 
         val changes = mutableMapOf<String, List<TextEdit>>()
         for (document in request.relatedDocuments.filterIsInstance<LatexDocument>()) {
@@ -29,6 +29,6 @@ object LatexLabelRenamer : FeatureProvider<RenameParams, List<WorkspaceEdit>> {
             changes[document.uri.toString()] = edits
         }
 
-        return listOf(WorkspaceEdit(changes))
+        return WorkspaceEdit(changes)
     }
 }
diff --git a/src/test/kotlin/texlab/hover/BibtexEntryTypeHoverProviderTests.kt b/src/test/kotlin/texlab/hover/BibtexEntryTypeHoverProviderTests.kt
index ec1af402..9957ada2 100644
--- a/src/test/kotlin/texlab/hover/BibtexEntryTypeHoverProviderTests.kt
+++ b/src/test/kotlin/texlab/hover/BibtexEntryTypeHoverProviderTests.kt
@@ -1,7 +1,8 @@
 package texlab.hover
 
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Assertions.assertNotNull
+import org.junit.jupiter.api.Assertions.assertNull
 import org.junit.jupiter.api.Test
 import texlab.WorkspaceBuilder
 
@@ -12,7 +13,7 @@ class BibtexEntryTypeHoverProviderTests {
                 .document("foo.bib", "@article")
                 .hover("foo.bib", 0, 2)
                 .let { BibtexEntryTypeHoverProvider.get(it) }
-                .also { assertTrue(it.isNotEmpty()) }
+                .also { assertNotNull(it) }
     }
 
     @Test
@@ -21,7 +22,7 @@ class BibtexEntryTypeHoverProviderTests {
                 .document("foo.bib", "@article{foo, bar = {baz}}")
                 .hover("foo.bib", 0, 10)
                 .let { BibtexEntryTypeHoverProvider.get(it) }
-                .also { assertTrue(it.isEmpty()) }
+                .also { assertNull(it) }
     }
 
     @Test
@@ -30,6 +31,6 @@ class BibtexEntryTypeHoverProviderTests {
                 .document("foo.tex", "")
                 .hover("foo.tex", 0, 0)
                 .let { BibtexEntryTypeHoverProvider.get(it) }
-                .also { assertTrue(it.isEmpty()) }
+                .also { assertNull(it) }
     }
 }
diff --git a/src/test/kotlin/texlab/hover/BibtexFieldHoverProviderTests.kt b/src/test/kotlin/texlab/hover/BibtexFieldHoverProviderTests.kt
index 90ac31f9..5cb7a225 100644
--- a/src/test/kotlin/texlab/hover/BibtexFieldHoverProviderTests.kt
+++ b/src/test/kotlin/texlab/hover/BibtexFieldHoverProviderTests.kt
@@ -1,7 +1,8 @@
 package texlab.hover
 
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertTrue
+import org.junit.jupiter.api.Assertions.assertNotNull
+import org.junit.jupiter.api.Assertions.assertNull
 import org.junit.jupiter.api.Test
 import texlab.WorkspaceBuilder
 
@@ -12,7 +13,7 @@ class BibtexFieldHoverProviderTests {
                 .document("foo.bib", "@article{foo, author = }")
                 .hover("foo.bib", 0, 15)
                 .let { BibtexFieldHoverProvider.get(it) }
-                .also { assertTrue(it.isNotEmpty()) }
+                .also { assertNotNull(it) }
     }
 
     @Test
@@ -21,7 +22,7 @@ class BibtexFieldHoverProviderTests {
                 .document("foo.bib", "@article{foo, author = {bar}}")
                 .hover("foo.bib", 0, 5)
                 .let { BibtexFieldHoverProvider.get(it) }
-                .also { assertTrue(it.isEmpty()) }
+                .also { assertNull(it) }
     }
 
     @Test
@@ -30,6 +31,6 @@ class BibtexFieldHoverProviderTests {
                 .document("foo.tex", "")
                 .hover("foo.tex", 0, 0)
                 .let { BibtexFieldHoverProvider.get(it) }
-                .also { assertTrue(it.isEmpty()) }
+                .also { assertNull(it) }
     }
 }
diff --git a/src/test/kotlin/texlab/provider/FeatureProviderTests.kt b/src/test/kotlin/texlab/provider/FeatureProviderTests.kt
index 7abf8f7a..e6b5a52a 100644
--- a/src/test/kotlin/texlab/provider/FeatureProviderTests.kt
+++ b/src/test/kotlin/texlab/provider/FeatureProviderTests.kt
@@ -1,8 +1,7 @@
 package texlab.provider
 
 import kotlinx.coroutines.runBlocking
-import org.junit.jupiter.api.Assertions.assertEquals
-import org.junit.jupiter.api.Assertions.assertNotNull
+import org.junit.jupiter.api.Assertions.*
 import org.junit.jupiter.api.Test
 import texlab.WorkspaceBuilder
 
@@ -51,4 +50,30 @@ class FeatureProviderTests {
         assertEquals(firstProvider.number, result[0])
         assertEquals(secondProvider.number, result[1])
     }
+
+    @Test
+    fun `it should return a result when a provider has a result`() = runBlocking {
+        val request = WorkspaceBuilder()
+                .document("foo.tex", "")
+                .request("foo.tex") {}
+
+        val firstProvider = NumberProvider(null)
+        val secondProvider = NumberProvider(2)
+        val provider = FeatureProvider.choice(firstProvider, secondProvider)
+        val result = provider.get(request)
+        assertEquals(result, secondProvider.number)
+    }
+
+    @Test
+    fun `it should return nothing when no provider has a result`() = runBlocking {
+        val request = WorkspaceBuilder()
+                .document("foo.tex", "")
+                .request("foo.tex") {}
+
+        val firstProvider = NumberProvider(null)
+        val secondProvider = NumberProvider(null)
+        val provider = FeatureProvider.choice(firstProvider, secondProvider)
+        val result = provider.get(request)
+        assertNull(result)
+    }
 }
diff --git a/src/test/kotlin/texlab/rename/BibtexEntryRenamerTests.kt b/src/test/kotlin/texlab/rename/BibtexEntryRenamerTests.kt
index e966b0f4..00ac83c8 100644
--- a/src/test/kotlin/texlab/rename/BibtexEntryRenamerTests.kt
+++ b/src/test/kotlin/texlab/rename/BibtexEntryRenamerTests.kt
@@ -20,7 +20,7 @@ class BibtexEntryRenamerTests {
 
         val edit = builder
                 .rename(document, line, character, "qux")
-                .let { BibtexEntryRenamer.get(it).first() }
+                .let { BibtexEntryRenamer.get(it)!! }
 
         assertEquals(2, edit.changes.size)
 
@@ -42,7 +42,7 @@ class BibtexEntryRenamerTests {
         WorkspaceBuilder()
                 .document("foo.bib", "@article{foo, bar = baz}")
                 .rename("foo.bib", 0, 14, "qux")
-                .let { BibtexEntryRenamer.get(it).firstOrNull() }
+                .let { BibtexEntryRenamer.get(it) }
                 .also { assertNull(it) }
     }
 
@@ -51,7 +51,7 @@ class BibtexEntryRenamerTests {
         WorkspaceBuilder()
                 .document("foo.tex", "")
                 .rename("foo.tex", 0, 0, "bar")
-                .let { BibtexEntryRenamer.get(it).firstOrNull() }
+                .let { BibtexEntryRenamer.get(it) }
                 .also { assertNull(it) }
     }
 }
diff --git a/src/test/kotlin/texlab/rename/LatexCommandRenamerTests.kt b/src/test/kotlin/texlab/rename/LatexCommandRenamerTests.kt
index 127a5c9e..6d1d6afb 100644
--- a/src/test/kotlin/texlab/rename/LatexCommandRenamerTests.kt
+++ b/src/test/kotlin/texlab/rename/LatexCommandRenamerTests.kt
@@ -17,7 +17,7 @@ class LatexCommandRenamerTests {
 
         val edit = builder
                 .rename("foo.tex", 1, 2, "qux")
-                .let { LatexCommandRenamer.get(it).first() }
+                .let { LatexCommandRenamer.get(it)!! }
 
         assertEquals(2, edit.changes.size)
 
@@ -39,7 +39,7 @@ class LatexCommandRenamerTests {
         WorkspaceBuilder()
                 .document("foo.bib", "\\foo \\bar")
                 .rename("foo.bib", 0, 1, "baz")
-                .let { LatexCommandRenamer.get(it).firstOrNull() }
+                .let { LatexCommandRenamer.get(it) }
                 .also { Assertions.assertNull(it) }
     }
 }
diff --git a/src/test/kotlin/texlab/rename/LatexEnvironmentRenamerTests.kt b/src/test/kotlin/texlab/rename/LatexEnvironmentRenamerTests.kt
index 7bc78a61..5d935536 100644
--- a/src/test/kotlin/texlab/rename/LatexEnvironmentRenamerTests.kt
+++ b/src/test/kotlin/texlab/rename/LatexEnvironmentRenamerTests.kt
@@ -14,7 +14,7 @@ class LatexEnvironmentRenamerTests {
         val edit = WorkspaceBuilder()
                 .document("foo.tex", "\\begin{foo}\n\\end{bar}")
                 .rename("foo.tex", 0, 8, "baz")
-                .let { LatexEnvironmentRenamer.get(it).first() }
+                .let { LatexEnvironmentRenamer.get(it)!! }
 
         assertEquals(1, edit.changes.keys.size)
         val changes = edit.changes.getValue(edit.changes.keys.first())
@@ -30,7 +30,7 @@ class LatexEnvironmentRenamerTests {
         WorkspaceBuilder()
                 .document("foo.tex", "\\begin{foo}\n\\end{bar}")
                 .rename("foo.tex", 0, 5, "baz")
-                .let { LatexEnvironmentRenamer.get(it).firstOrNull() }
+                .let { LatexEnvironmentRenamer.get(it) }
                 .also { assertNull(it) }
     }
 
@@ -39,7 +39,7 @@ class LatexEnvironmentRenamerTests {
         WorkspaceBuilder()
                 .document("foo.bib", "\\begin{foo}\n\\end{bar}")
                 .rename("foo.bib", 0, 8, "baz")
-                .let { LatexEnvironmentRenamer.get(it).firstOrNull() }
+                .let { LatexEnvironmentRenamer.get(it) }
                 .also { assertNull(it) }
     }
 }
diff --git a/src/test/kotlin/texlab/rename/LatexLabelRenamerTests.kt b/src/test/kotlin/texlab/rename/LatexLabelRenamerTests.kt
index 82b1bc53..edf75758 100644
--- a/src/test/kotlin/texlab/rename/LatexLabelRenamerTests.kt
+++ b/src/test/kotlin/texlab/rename/LatexLabelRenamerTests.kt
@@ -20,7 +20,7 @@ class LatexLabelRenamerTests {
                 .document("bar.tex", "\\ref{foo}")
         val edit = builder
                 .rename(document, line, character, "bar")
-                .let { LatexLabelRenamer.get(it).first() }
+                .let { LatexLabelRenamer.get(it)!! }
 
         Assertions.assertEquals(2, edit.changes.size)
 
@@ -42,7 +42,7 @@ class LatexLabelRenamerTests {
         WorkspaceBuilder()
                 .document("foo.tex", "\\foo{bar}")
                 .rename("foo.tex", 0, 5, "baz")
-                .let { LatexLabelRenamer.get(it).firstOrNull() }
+                .let { LatexLabelRenamer.get(it) }
                 .also { assertNull(it) }
     }
 
@@ -51,7 +51,7 @@ class LatexLabelRenamerTests {
         WorkspaceBuilder()
                 .document("foo.bib", "")
                 .rename("foo.bib", 0, 0, "bar")
-                .let { LatexLabelRenamer.get(it).firstOrNull() }
+                .let { LatexLabelRenamer.get(it) }
                 .also { assertNull(it) }
     }
 }