From f0a3d2bf92cd59d3c068246109c5832f83d3d150 Mon Sep 17 00:00:00 2001
From: Andrew Branch <andrew@wheream.io>
Date: Fri, 19 Apr 2019 09:44:42 -0700
Subject: [PATCH] Filter out zero-width selections

---
 src/services/smartSelection.ts                | 11 ++++---
 .../unittests/tsserver/smartSelection.ts      | 33 ++++++++++++++++++-
 2 files changed, 39 insertions(+), 5 deletions(-)

diff --git a/src/services/smartSelection.ts b/src/services/smartSelection.ts
index ba2ec60e9c5..ddd3c75c2c7 100644
--- a/src/services/smartSelection.ts
+++ b/src/services/smartSelection.ts
@@ -70,10 +70,13 @@ namespace ts.SmartSelectionRange {
         return selectionRange;
 
         function pushSelectionRange(start: number, end: number): void {
-            // Skip ranges that are identical to the parent
-            const textSpan = createTextSpanFromBounds(start, end);
-            if (!selectionRange || !textSpansEqual(textSpan, selectionRange.textSpan)) {
-                selectionRange = { textSpan, ...selectionRange && { parent: selectionRange } };
+            // Skip empty ranges
+            if (start !== end) {
+                // Skip ranges that are identical to the parent
+                const textSpan = createTextSpanFromBounds(start, end);
+                if (!selectionRange || !textSpansEqual(textSpan, selectionRange.textSpan)) {
+                    selectionRange = { textSpan, ...selectionRange && { parent: selectionRange } };
+                }
             }
         }
     }
diff --git a/src/testRunner/unittests/tsserver/smartSelection.ts b/src/testRunner/unittests/tsserver/smartSelection.ts
index 5d4113d3f97..fca96ab848e 100644
--- a/src/testRunner/unittests/tsserver/smartSelection.ts
+++ b/src/testRunner/unittests/tsserver/smartSelection.ts
@@ -12,7 +12,7 @@ namespace ts.projectSystem {
         };
     }
 
-    describe("unittests:: tsserver:: selectionRange", () => {
+    describe("unittests:: tsserver:: smartSelection", () => {
         it("works for simple JavaScript", () => {
             const getSmartSelectionRange = setup("/file.js", `
 class Foo {
@@ -652,5 +652,36 @@ function square(x) {
                         start: { line: 1, offset: 1 },
                         end: { line: 1, offset: 13 } } } }]);
         });
+
+        it("never returns empty ranges", () => {
+            const getSmartSelectionRange = setup("/file.ts", `
+class HomePage {
+    componentDidMount() {
+        if (this.props.username) {
+            return '';
+        }
+    }
+}`);
+            const locations = getSmartSelectionRange([
+                { line: 3, offset: 23 }, // componentDidMount(/**/)
+                { line: 4, offset: 32 }, // username/**/)
+                { line: 5, offset: 21 }, // return '/**/'
+            ]);
+
+            assert.deepEqual(locations![0].textSpan, { // this.props.username
+                start: { line: 3, offset: 23 },
+                end: { line: 3, offset: 24 },
+            });
+
+            assert.deepEqual(locations![1].textSpan, { // this.props.username
+                start: { line: 4, offset: 32 },
+                end: { line: 4, offset: 33 },
+            });
+
+            assert.deepEqual(locations![2].textSpan, { // ''
+                start: { line: 5, offset: 20 },
+                end: { line: 5, offset: 22 },
+            });
+        });
     });
 }