fix(project): keep a newer project's preferences when an older load finishes last

Opening a project reloads its preferences file in the background without
waiting. When two projects opened close together, the earlier project's
reload could finish last and point the project preferences back at the
project that had just closed, leaving settings like spaceUnits at their
defaults. This made the PreferencesManager integration tests flaky on CI.

The reload now stops if the project root changed while it read the
files. A regression test holds one project's reads while the next
project opens, and fails without the fix.

Author: abose

src/project/ProjectManager.js

@@ -1117,6 +1117,13 @@ define(function (require, exports, module) {
                 bracketsPrefFile = root.fullPath + SETTINGS_FILENAME_BRACKETS;
             const statusPhoenix = await _validateProjectPreferencesFile(phoenixPrefFile);
             const statusBrackets = await _validateProjectPreferencesFile(bracketsPrefFile);
+            // Another project opened while the files were read. Its own reload
+            // applies; finishing this one would point the project preferences
+            // back at the project that was just closed.
+            const currentRoot = getProjectRoot();
+            if (!currentRoot || currentRoot.fullPath !== root.fullPath) {
+                return;
+            }
             let prefFileToUse = phoenixPrefFile;
             if(statusPhoenix === PREF_NO_FILE && statusBrackets !== PREF_NO_FILE) {
                 prefFileToUse = bracketsPrefFile;

test/spec/PreferencesManager-integ-test.js

@@ -19,7 +19,7 @@
  *
  */
 
-/*global describe, it, expect, beforeEach, beforeAll, afterAll, awaitsFor, awaitsForDone */
+/*global describe, it, expect, beforeEach, beforeAll, afterAll, awaitsFor, awaitsForDone, spyOn */
 
 define(function (require, exports, module) {
 
@@ -84,6 +84,58 @@ define(function (require, exports, module) {
             await _verifySinglePreference(".brackets.json", 6);
         }, 100000);
 
+        it("should keep a newer project's preferences when an older project's load finishes last", async function () {
+            const FileUtils = testWindow.brackets.test.FileUtils;
+            const projectWithoutSettings = SpecRunnerUtils.getTestPath("/spec/WorkingSetView-test-files");
+            const realReadAsText = FileUtils.readAsText;
+            let releaseStaleReads;
+            const staleReadsReleased = new Promise(function (resolve) {
+                releaseStaleReads = resolve;
+            });
+            let heldReads = 0, settledReads = 0;
+            // Hold the settings-free project's preference reads until the next
+            // project has loaded, so its reload finishes last.
+            spyOn(FileUtils, "readAsText").and.callFake(function (file, ...args) {
+                const result = realReadAsText.call(FileUtils, file, ...args);
+                const name = file.fullPath.split("/").pop();
+                if (!file.fullPath.startsWith(projectWithoutSettings + "/") ||
+                    (name !== ".phcode.json" && name !== ".brackets.json")) {
+                    return result;
+                }
+                heldReads++;
+                const held = new testWindow.$.Deferred();
+                staleReadsReleased.then(function () {
+                    result.always(function () {
+                        settledReads++;
+                    }).done(held.resolve).fail(held.reject);
+                });
+                return held.promise();
+            });
+            spyOn(PreferencesManager, "_setProjectSettingsFile").and.callThrough();
+            try {
+                // Start elsewhere, so opening the settings-free project is a real switch.
+                await SpecRunnerUtils.loadProjectInTestWindow(testPath);
+                await SpecRunnerUtils.loadProjectInTestWindow(projectWithoutSettings);
+                await SpecRunnerUtils.loadProjectInTestWindow(testPathBracketsPrefsOnly);
+                await awaitsForDone(SpecRunnerUtils.openProjectFiles(".brackets.json"));
+                await awaitsFor(()=>{
+                    return PreferencesManager.get("spaceUnits") === 6;
+                }, "space units to be 6 from the newer project", 10000);
+                expect(heldReads).toBeGreaterThan(0);
+            } finally {
+                releaseStaleReads();
+            }
+            // Every held read settles, and whatever the older reload does next
+            // runs before the next check.
+            await awaitsFor(()=>{
+                return settledReads === heldReads;
+            }, "the older project's reads to finish", 10000);
+
+            const lastSettingsFile = PreferencesManager._setProjectSettingsFile.calls.mostRecent().args[0];
+            expect(lastSettingsFile.startsWith(testPathBracketsPrefsOnly + "/")).toBeTrue();
+            expect(PreferencesManager.get("spaceUnits")).toBe(6);
+        }, 30000);
+
         it("should .phcode.json take precedence over .brackets.json", async function () {
             await SpecRunnerUtils.loadProjectInTestWindow(testPathBothPrefs);
             await awaitsForDone(SpecRunnerUtils.openProjectFiles(".phcode.json"));