From 7f347025de951042ec4543eaede107721b775687 Mon Sep 17 00:00:00 2001
From: Andrew Casey <andrew.casey@microsoft.com>
Date: Tue, 23 Jan 2018 11:07:59 -0800
Subject: [PATCH 1/2] Handle extraction ranges including case clause
 expressions

(mostly by rejecting them)

Fixes #20559
---
 src/harness/unittests/extractRanges.ts  | 46 +++++++++++++++++++++++++
 src/services/refactors/extractSymbol.ts | 11 ++++++
 2 files changed, 57 insertions(+)

diff --git a/src/harness/unittests/extractRanges.ts b/src/harness/unittests/extractRanges.ts
index 493c9639c3d..2810f323abf 100644
--- a/src/harness/unittests/extractRanges.ts
+++ b/src/harness/unittests/extractRanges.ts
@@ -365,6 +365,52 @@ switch (x) {
             refactor.extractSymbol.Messages.cannotExtractRange.message
         ]);
 
+        testExtractRangeFailed("extractRangeFailed14",
+        `
+            switch(1) {
+                case [#|1:
+                    break;|]
+            }
+        `,
+        [
+            refactor.extractSymbol.Messages.cannotExtractRange.message
+        ]);
+
+        testExtractRangeFailed("extractRangeFailed15",
+        `
+            switch(1) {
+                case [#|1:
+                    break|];
+            }
+        `,
+        [
+            refactor.extractSymbol.Messages.cannotExtractRange.message
+        ]);
+
+        // Documentation only - it would be nice if the result were [$|1|]
+        testExtractRangeFailed("extractRangeFailed16",
+        `
+            switch(1) {
+                [#|case 1|]:
+                    break;
+            }
+        `,
+        [
+            refactor.extractSymbol.Messages.cannotExtractRange.message
+        ]);
+
+        // Documentation only - it would be nice if the result were [$|1|]
+        testExtractRangeFailed("extractRangeFailed17",
+        `
+            switch(1) {
+                [#|case 1:|]
+                    break;
+            }
+        `,
+        [
+            refactor.extractSymbol.Messages.cannotExtractRange.message
+        ]);
+
         testExtractRangeFailed("extract-method-not-for-token-expression-statement", `[#|a|]`, [refactor.extractSymbol.Messages.cannotExtractIdentifier.message]);
     });
 }
\ No newline at end of file
diff --git a/src/services/refactors/extractSymbol.ts b/src/services/refactors/extractSymbol.ts
index 479c387fc65..efdf9b233a9 100644
--- a/src/services/refactors/extractSymbol.ts
+++ b/src/services/refactors/extractSymbol.ts
@@ -235,6 +235,17 @@ namespace ts.refactor.extractSymbol {
                     break;
                 }
             }
+
+            if (!statements.length) {
+                // https://github.com/Microsoft/TypeScript/issues/20559
+                // Ranges like [|case 1: break;|] will fail to populate `statements` because
+                // they will never find `start` in `start.parent.statements`.
+                // Consider: We could support ranges like [|case 1:|] by refining them to just
+                // the expression.
+                Debug.assert(isCaseClause(start.parent) && span.start < start.parent.expression.end);
+                return { errors: [createFileDiagnostic(sourceFile, span.start, length, Messages.cannotExtractRange)] };
+            }
+
             return { targetRange: { range: statements, facts: rangeFacts, declarations } };
         }
 

From f7f81254d3499f84c35229ab8dfe77fa6e27fa4c Mon Sep 17 00:00:00 2001
From: Andrew Casey <andrew.casey@microsoft.com>
Date: Wed, 24 Jan 2018 12:46:13 -0800
Subject: [PATCH 2/2] Remove incorrect assert

---
 src/harness/unittests/extractRanges.ts  | 6 ++++++
 src/services/refactors/extractSymbol.ts | 1 -
 2 files changed, 6 insertions(+), 1 deletion(-)

diff --git a/src/harness/unittests/extractRanges.ts b/src/harness/unittests/extractRanges.ts
index 2810f323abf..00fbf334b38 100644
--- a/src/harness/unittests/extractRanges.ts
+++ b/src/harness/unittests/extractRanges.ts
@@ -411,6 +411,12 @@ switch (x) {
             refactor.extractSymbol.Messages.cannotExtractRange.message
         ]);
 
+        testExtractRangeFailed("extractRangeFailed18",
+        `[#|{ 1;|] }`,
+        [
+            refactor.extractSymbol.Messages.cannotExtractRange.message
+        ]);
+
         testExtractRangeFailed("extract-method-not-for-token-expression-statement", `[#|a|]`, [refactor.extractSymbol.Messages.cannotExtractIdentifier.message]);
     });
 }
\ No newline at end of file
diff --git a/src/services/refactors/extractSymbol.ts b/src/services/refactors/extractSymbol.ts
index efdf9b233a9..3f79a0755e1 100644
--- a/src/services/refactors/extractSymbol.ts
+++ b/src/services/refactors/extractSymbol.ts
@@ -242,7 +242,6 @@ namespace ts.refactor.extractSymbol {
                 // they will never find `start` in `start.parent.statements`.
                 // Consider: We could support ranges like [|case 1:|] by refining them to just
                 // the expression.
-                Debug.assert(isCaseClause(start.parent) && span.start < start.parent.expression.end);
                 return { errors: [createFileDiagnostic(sourceFile, span.start, length, Messages.cannotExtractRange)] };
             }