Generalize extract method to handle constants as well

Major changes:

1) Instead of skipping undesirable scopes, include them and mark them
with errors.  Constants can be extracted into more scopes.

2) Update the tests to call through the "public" API.  This caused some
baseline changes.

3) Rename refactoring to "Extract Symbol" for generality.

4) Return a second ApplicableRefactorInfo for constants.  Distinguish
the two by splitting the action name.

Author: amcasey

src/compiler/diagnosticMessages.json

@@ -3703,13 +3703,23 @@
         "code": 95002
     },
 
-    "Extract function": {
+    "Extract symbol": {
         "category": "Message",
         "code": 95003
     },
 
     "Extract to {0}": {
         "category": "Message",
         "code": 95004
+    },
+
+    "Extract function": {
+        "category": "Message",
+        "code": 95005
+    },
+
+    "Extract constant": {
+        "category": "Message",
+        "code": 95006
     }
 }

src/harness/unittests/extractMethods.ts

@@ -105,7 +105,7 @@ namespace ts {
             if (!selectionRange) {
                 throw new Error(`Test ${s} does not specify selection range`);
             }
-            const result = refactor.extractMethod.getRangeToExtract(file, createTextSpanFromBounds(selectionRange.start, selectionRange.end));
+            const result = refactor.extractSymbol.getRangeToExtract(file, createTextSpanFromBounds(selectionRange.start, selectionRange.end));
             assert(result.targetRange === undefined, "failure expected");
             const sortedErrors = result.errors.map(e => <string>e.messageText).sort();
             assert.deepEqual(sortedErrors, expectedErrors.sort(), "unexpected errors");
@@ -119,7 +119,7 @@ namespace ts {
         if (!selectionRange) {
             throw new Error(`Test ${s} does not specify selection range`);
         }
-        const result = refactor.extractMethod.getRangeToExtract(f, createTextSpanFromBounds(selectionRange.start, selectionRange.end));
+        const result = refactor.extractSymbol.getRangeToExtract(f, createTextSpanFromBounds(selectionRange.start, selectionRange.end));
         const expectedRange = t.ranges.get("extracted");
         if (expectedRange) {
             let start: number, end: number;
@@ -407,7 +407,7 @@ function test(x: number) {
         testExtractRangeFailed("extractRangeFailed9",
         `var x = ([#||]1 + 2);`,
         [
-            "Statement or expression expected."
+            "Cannot extract empty range."
         ]);
 
         testExtractRangeFailed("extract-method-not-for-token-expression-statement", `[#|a|]`, ["Select more than a single identifier."]);
@@ -604,15 +604,15 @@ function test(x: number) {
         // doesn't handle type parameter shadowing.
         testExtractMethod("extractMethod14",
             `function F<T>(t1: T) {
-    function F<T>(t2: T) {
+    function G<T>(t2: T) {
         [#|t1.toString();
         t2.toString();|]
     }
 }`);
         // Confirm that the constraint is preserved.
         testExtractMethod("extractMethod15",
             `function F<T>(t1: T) {
-    function F<U extends T[]>(t2: U) {
+    function G<U extends T[]>(t2: U) {
         [#|t2.toString();|]
     }
 }`);
@@ -799,19 +799,20 @@ function parsePrimaryExpression(): any {
                     newLineCharacter,
                     program,
                     file: sourceFile,
-                    startPosition: -1,
+                    startPosition: selectionRange.start,
+                    endPosition: selectionRange.end,
                     rulesProvider: getRuleProvider()
                 };
-                const result = refactor.extractMethod.getRangeToExtract(sourceFile, createTextSpanFromBounds(selectionRange.start, selectionRange.end));
-                assert.equal(result.errors, undefined, "expect no errors");
-                const results = refactor.extractMethod.getPossibleExtractions(result.targetRange, context);
+                const rangeToExtract = refactor.extractSymbol.getRangeToExtract(sourceFile, createTextSpanFromBounds(selectionRange.start, selectionRange.end));
+                assert.equal(rangeToExtract.errors, undefined, "expect no errors");
+                const actions = refactor.extractSymbol.getAvailableActions(context)[0].actions; // TODO (acasey): smarter index
                 const data: string[] = [];
                 data.push(`// ==ORIGINAL==`);
                 data.push(sourceFile.text);
-                for (const r of results) {
-                    const { renameLocation, edits } = refactor.extractMethod.getExtractionAtIndex(result.targetRange, context, results.indexOf(r));
+                for (const action of actions) {
+                    const { renameLocation, edits } = refactor.extractSymbol.getEditsForAction(context, action.name);
                     assert.lengthOf(edits, 1);
-                    data.push(`// ==SCOPE::${r.scopeDescription}==`);
+                    data.push(`// ==SCOPE::${action.description}==`);
                     const newText = textChanges.applyChanges(sourceFile.text, edits[0].textChanges);
                     const newTextWithRename = newText.slice(0, renameLocation) + "/*RENAME*/" + newText.slice(renameLocation);
                     data.push(newTextWithRename);