Handle extracting case clause expression as constant

amcasey · amcasey · commit 4f11dd68abf9 · 2018-01-23T11:08:45.000-08:00
diff --git a/src/harness/unittests/extractConstants.ts b/src/harness/unittests/extractConstants.ts
@@ -273,6 +273,13 @@ let i: I = [#|{ a: 1 }|];
 const myObj: { member(x: number, y: string): void } = {
     member: [#|(x, y) => x + y|],
 }
+`);
+
+        testExtractConstant("extractConstant_CaseClauseExpression", `
+switch (1) {
+    case [#|1|]:
+        break;
+}
 `);
     });
 
diff --git a/src/services/refactors/extractSymbol.ts b/src/services/refactors/extractSymbol.ts
@@ -1321,6 +1321,13 @@ namespace ts.refactor.extractSymbol {
                     }
                     prevStatement = statement;
                 }
+
+                if (!prevStatement && isCaseClause(curr)) {
+                    // We must have been in the expression of the case clause.
+                    Debug.assert(isSwitchStatement(curr.parent.parent));
+                    return curr.parent.parent;
+                }
+
                 // There must be at least one statement since we started in one.
                 Debug.assert(prevStatement !== undefined);
                 return prevStatement;
diff --git a/tests/baselines/reference/extractConstant/extractConstant_CaseClauseExpression.js b/tests/baselines/reference/extractConstant/extractConstant_CaseClauseExpression.js
@@ -0,0 +1,13 @@
+// ==ORIGINAL==
+
+switch (1) {
+    case /*[#|*/1/*|]*/:
+        break;
+}
+
+// ==SCOPE::Extract to constant in enclosing scope==
+const newLocal = 1;
+switch (1) {
+    case /*RENAME*/newLocal:
+        break;
+}
diff --git a/tests/baselines/reference/extractConstant/extractConstant_CaseClauseExpression.ts b/tests/baselines/reference/extractConstant/extractConstant_CaseClauseExpression.ts
@@ -0,0 +1,13 @@
+// ==ORIGINAL==
+
+switch (1) {
+    case /*[#|*/1/*|]*/:
+        break;
+}
+
+// ==SCOPE::Extract to constant in enclosing scope==
+const newLocal = 1;
+switch (1) {
+    case /*RENAME*/newLocal:
+        break;
+}

Original file line number	Diff line number	Diff line change
`@@ -1321,6 +1321,13 @@ namespace ts.refactor.extractSymbol {`
`1321`	`1321`	`}`
`1322`	`1322`	`prevStatement = statement;`
`1323`	`1323`	`}`
	`1324`	`+`
	`1325`	`+ if (!prevStatement && isCaseClause(curr)) {`
	`1326`	`+ // We must have been in the expression of the case clause.`
	`1327`	`+ Debug.assert(isSwitchStatement(curr.parent.parent));`
	`1328`	`+ return curr.parent.parent;`
	`1329`	`+ }`
	`1330`	`+`
`1324`	`1331`	`// There must be at least one statement since we started in one.`
`1325`	`1332`	`Debug.assert(prevStatement !== undefined);`
`1326`	`1333`	`return prevStatement;`