Add email function tests to test.get.js (addresses review feedback)

- Move all tests to test.get.js instead of separate file
- Remove over-specific mocks from beforeEach
- Put test-specific mocks inside individual tests
- Focus on behavior testing, not implementation details
- Keep only valuable tests that protect against regressions
- Add 182 lines of behavior-focused tests
- Test return types, edge cases, and error handling

Tests added:
- get.email_subject() - 2 tests (null handling, fallback)
- get.email_ids() - 3 tests (return type, empty, null handling)
- get.compose_ids() - 2 tests (return type, empty)
- get.thread_id() - 3 tests (extraction, null, empty)
- get.email_id() - 1 test (alias verification)
- get.visible_emails() - 2 tests (return type, empty)
- get.selected_emails_data() - 2 tests (return type, empty)
- get.search_query() - 3 tests (extraction, non-search, empty)
- get.unread_emails() - 1 test (return type)
- Error handling - 3 tests (null document, missing location, malformed)

Total: 22 behavior-focused tests covering 10 email functions

Author: 0xsatoshi99

test/test.get.js

@@ -121,4 +121,186 @@ describe("Get functions", () => {
             assert.equal(result[3].index, 2);
         });
     });
+
+    describe("get.email_subject", () => {
+        it("returns empty string when no subject element found", () => {
+            // Mock returns null - test behavior, not implementation
+            global.document.querySelector = () => null;
+            const subject = gmail.get.email_subject();
+            assert.strictEqual(subject, '');
+        });
+
+        it("handles alternative subject selector as fallback", () => {
+            // Test fallback behavior exists
+            global.document.querySelector = (selector) => {
+                if (selector === '.nH .ha h2') {
+                    return { textContent: 'Fallback Subject' };
+                }
+                return null;
+            };
+            const subject = gmail.get.email_subject();
+            assert.strictEqual(subject, 'Fallback Subject');
+        });
+    });
+
+    describe("get.email_ids", () => {
+        it("returns array of email IDs", () => {
+            // Test return type - behavior focused
+            const ids = gmail.get.email_ids();
+            assert(Array.isArray(ids));
+        });
+
+        it("returns empty array when no emails found", () => {
+            // Test edge case behavior
+            global.document.getElementsByClassName = () => [];
+            const ids = gmail.get.email_ids();
+            assert(Array.isArray(ids));
+            assert.strictEqual(ids.length, 0);
+        });
+
+        it("handles null elements gracefully", () => {
+            // Test error handling
+            global.document.getElementsByClassName = () => [null, undefined];
+            const ids = gmail.get.email_ids();
+            assert(Array.isArray(ids));
+        });
+    });
+
+    describe("get.compose_ids", () => {
+        it("returns array of compose window IDs", () => {
+            // Test return type
+            const ids = gmail.get.compose_ids();
+            assert(Array.isArray(ids));
+        });
+
+        it("returns empty array when no compose windows", () => {
+            // Test edge case
+            global.document.querySelectorAll = () => [];
+            const ids = gmail.get.compose_ids();
+            assert(Array.isArray(ids));
+            assert.strictEqual(ids.length, 0);
+        });
+    });
+
+    describe("get.thread_id", () => {
+        it("extracts thread ID from URL hash", () => {
+            // Test basic functionality
+            global.window.location.hash = "#inbox/1234567890abcdef";
+            const threadId = gmail.get.thread_id();
+            assert.strictEqual(threadId, '1234567890abcdef');
+        });
+
+        it("returns null when no thread ID in hash", () => {
+            // Test null case
+            global.window.location.hash = "#inbox";
+            const threadId = gmail.get.thread_id();
+            assert.strictEqual(threadId, null);
+        });
+
+        it("handles empty hash", () => {
+            // Test edge case
+            global.window.location.hash = "";
+            const threadId = gmail.get.thread_id();
+            assert.strictEqual(threadId, null);
+        });
+    });
+
+    describe("get.email_id", () => {
+        it("returns thread ID (alias test)", () => {
+            // Test that email_id is an alias for thread_id
+            global.window.location.hash = "#inbox/1234567890abcdef";
+            const emailId = gmail.get.email_id();
+            const threadId = gmail.get.thread_id();
+            assert.strictEqual(emailId, threadId);
+        });
+    });
+
+    describe("get.visible_emails", () => {
+        it("returns array of visible email objects", () => {
+            // Test return type
+            const emails = gmail.get.visible_emails();
+            assert(Array.isArray(emails));
+        });
+
+        it("returns empty array when no visible emails", () => {
+            // Test edge case
+            global.document.querySelectorAll = () => [];
+            const emails = gmail.get.visible_emails();
+            assert(Array.isArray(emails));
+            assert.strictEqual(emails.length, 0);
+        });
+    });
+
+    describe("get.selected_emails_data", () => {
+        it("returns array of selected email data", () => {
+            // Test return type
+            const data = gmail.get.selected_emails_data();
+            assert(Array.isArray(data));
+        });
+
+        it("returns empty array when no emails selected", () => {
+            // Test edge case
+            global.document.querySelectorAll = () => [];
+            const data = gmail.get.selected_emails_data();
+            assert(Array.isArray(data));
+            assert.strictEqual(data.length, 0);
+        });
+    });
+
+    describe("get.search_query", () => {
+        it("extracts search query from URL hash", () => {
+            // Test basic functionality
+            global.window.location.hash = "#search/test+query";
+            const query = gmail.get.search_query();
+            assert.strictEqual(query, 'test query');
+        });
+
+        it("returns empty string when not in search", () => {
+            // Test non-search case
+            global.window.location.hash = "#inbox";
+            const query = gmail.get.search_query();
+            assert.strictEqual(query, '');
+        });
+
+        it("handles empty search", () => {
+            // Test edge case
+            global.window.location.hash = "#search/";
+            const query = gmail.get.search_query();
+            assert.strictEqual(query, '');
+        });
+    });
+
+    describe("get.unread_emails", () => {
+        it("returns object with unread email counts", () => {
+            // Test return type
+            const unread = gmail.get.unread_emails();
+            assert(typeof unread === 'object');
+        });
+    });
+
+    describe("Error handling", () => {
+        it("handles null document gracefully", () => {
+            // Test robustness
+            global.document = null;
+            assert.doesNotThrow(() => {
+                gmail.get.email_subject();
+            });
+        });
+
+        it("handles missing window.location", () => {
+            // Test robustness
+            delete global.window.location;
+            assert.doesNotThrow(() => {
+                gmail.get.thread_id();
+            });
+        });
+
+        it("handles malformed hash values", () => {
+            // Test error handling
+            global.window.location.hash = "###invalid###";
+            assert.doesNotThrow(() => {
+                gmail.get.thread_id();
+            });
+        });
+    });
 });