Add tests to validate spans are returned when falling back from current culture to english.

src/EditorFeatures/Test2/IntelliSense/CompletionRulesTests.vb

@@ -3,6 +3,7 @@
 Imports System.Globalization
 Imports Microsoft.CodeAnalysis.Completion
 Imports Microsoft.CodeAnalysis.Editor.UnitTests.Workspaces
+Imports Microsoft.CodeAnalysis.Text
 
 Namespace Microsoft.CodeAnalysis.Editor.UnitTests.IntelliSense
     ' These tests adapted from David Kean's table at
@@ -10,7 +11,7 @@ Namespace Microsoft.CodeAnalysis.Editor.UnitTests.IntelliSense
     Public Class CompletionRulesTests
         <Fact>
         Public Sub TestMatchLowerCaseEnglishI()
-            Dim wordsToMatch = {"index", "Index", "işte", "İşte"}
+            Dim wordsToMatch = {"[|i|]ndex", "[|I|]ndex", "[|i|]şte", "[|İ|]şte"}
             Dim wordsToNotMatch = {"ırak"}
 
             TestMatches("i", wordsToMatch)
@@ -19,7 +20,7 @@ Namespace Microsoft.CodeAnalysis.Editor.UnitTests.IntelliSense
 
         <Fact>
         Public Sub TestMatchDottedUpperTurkishI()
-            Dim wordsToMatch = {"index", "işte", "İşte"}
+            Dim wordsToMatch = {"[|i|]ndex", "[|i|]şte", "[|İ|]şte"}
             Dim wordsToNotMatch = {"ırak", "Irak", "Index"}
 
             TestMatches("İ", wordsToMatch)
@@ -28,7 +29,7 @@ Namespace Microsoft.CodeAnalysis.Editor.UnitTests.IntelliSense
 
         <Fact>
         Public Sub TestMatchNonDottedLowerTurkishI()
-            Dim wordsToMatch = {"ırak", "Irak"}
+            Dim wordsToMatch = {"[|ı|]rak", "[|I|]rak"}
             Dim wordsToNotMatch = {"index", "işte", "İşte"}
 
             TestMatches("ı", wordsToMatch)
@@ -37,31 +38,48 @@ Namespace Microsoft.CodeAnalysis.Editor.UnitTests.IntelliSense
 
         <Fact>
         Public Sub TestMatchEnglishUpperI()
-            Dim wordsToMatch = {"Index", "index", "ırak", "Irak"}
+            ' In turkish-culture "I" will not match "index".  However, we want to verify that
+            ' the underlying completion helper will fallback to doing an en-us check if the
+            ' tr-tr check fails, and that it properly also returns the matched spans in this case.
+
+            Dim wordsToMatch = {"[|I|]ndex", "[|i|]ndex", "[|ı|]rak", "[|I|]rak"}
             Dim wordsToNotMatch = {"İşte"}
 
             TestMatches("I", wordsToMatch)
             TestNotMatches("I", wordsToNotMatch)
         End Sub
 
-        Private Sub TestMatches(v As String, wordsToMatch() As String)
+        Private Sub TestMatches(pattern As String, wordsToMatch() As String)
             Dim culture = New CultureInfo("tr-TR", useUserOverride:=False)
 
             Dim workspace = New TestWorkspace
             Dim helper = CompletionHelper.GetHelper(workspace, LanguageNames.CSharp)
-            For Each word In wordsToMatch
+
+            For Each wordMarkup In wordsToMatch
+                Dim word As String = Nothing
+                Dim wordMatchSpan As TextSpan = Nothing
+                MarkupTestFile.GetSpan(wordMarkup, word, wordMatchSpan)
+
                 Dim item = CompletionItem.Create(word)
-                Assert.True(helper.MatchesPattern(item.FilterText, v, culture), $"Expected item {word} does not match {v}")
+                Assert.True(helper.MatchesPattern(item.FilterText, pattern, culture), $"Expected item {word} does not match {pattern}")
+
+                Dim highlightedSpans = helper.GetHighlightedSpans(item.FilterText, pattern, culture)
+                Assert.NotEmpty(highlightedSpans)
+                Assert.Equal(1, highlightedSpans.Length)
+                Assert.Equal(wordMatchSpan, highlightedSpans(0))
             Next
         End Sub
 
-        Private Sub TestNotMatches(v As String, wordsToNotMatch() As String)
+        Private Sub TestNotMatches(pattern As String, wordsToNotMatch() As String)
             Dim culture = New CultureInfo("tr-TR", useUserOverride:=False)
             Dim workspace = New TestWorkspace
             Dim helper = CompletionHelper.GetHelper(workspace, LanguageNames.CSharp)
             For Each word In wordsToNotMatch
                 Dim item = CompletionItem.Create(word)
-                Assert.False(helper.MatchesPattern(item.FilterText, v, culture), $"Unexpected item {word} matches {v}")
+                Assert.False(helper.MatchesPattern(item.FilterText, pattern, culture), $"Unexpected item {word} matches {pattern}")
+
+                Dim highlightedSpans = helper.GetHighlightedSpans(item.FilterText, pattern, culture)
+                Assert.Empty(highlightedSpans)
             Next
         End Sub
     End Class