diff --git a/test/src/buffer-tests.el b/test/src/buffer-tests.el
index 3fae18011fb..6ed26e9316f 100644
--- a/test/src/buffer-tests.el
+++ b/test/src/buffer-tests.el
@@ -269,6 +269,43 @@ with parameters from the *Messages* buffer modification."
   (with-temp-buffer
     (should (eq (buffer-base-buffer (current-buffer)) nil))))
 
+(ert-deftest buffer-tests--basic-buffer-primitives ()
+  (let ((buf (generate-new-buffer " *buffer-tests-basic*")))
+    (unwind-protect
+        (progn
+          (should (bufferp buf))
+          (should (buffer-live-p buf))
+          (should (equal (buffer-name buf) " *buffer-tests-basic*"))
+          (should (eq (get-buffer " *buffer-tests-basic*") buf))
+          (should (eq (get-buffer buf) buf))
+          (should (eq (get-buffer-create " *buffer-tests-basic*") buf))
+          (with-current-buffer buf
+            (insert "abc")
+            (should (= (buffer-size) 3))
+            (should (eq (set-buffer buf) buf)))
+          (with-current-buffer buf
+            (let ((new-name (rename-buffer " *buffer-tests-renamed*" t)))
+              (should (equal new-name " *buffer-tests-renamed*"))
+              (should (eq (get-buffer new-name) buf))))
+          (should (memq buf (buffer-list))))
+      (when (buffer-live-p buf)
+        (kill-buffer buf)))
+    (should-not (buffer-live-p buf))))
+
+(ert-deftest buffer-tests--other-buffer ()
+  (let ((b1 (generate-new-buffer " *buffer-tests-ob1*"))
+        (b2 (generate-new-buffer " *buffer-tests-ob2*")))
+    (unwind-protect
+        (with-current-buffer b1
+          (let ((other (other-buffer (current-buffer) t)))
+            (should (bufferp other))
+            (should (buffer-live-p other))
+            (should-not (eq other (current-buffer)))))
+      (when (buffer-live-p b1)
+        (kill-buffer b1))
+      (when (buffer-live-p b2)
+        (kill-buffer b2)))))
+
 (ert-deftest buffer-tests--overlays-indirect-bug58928 ()
   (with-temp-buffer
     (insert "hello world")
diff --git a/test/src/data-tests.el b/test/src/data-tests.el
index deec9feead7..dbf85ed943b 100644
--- a/test/src/data-tests.el
+++ b/test/src/data-tests.el
@@ -860,6 +860,21 @@ comparing the subr with a much slower Lisp implementation."
     (data-tests-check-sign (% -1 -3) (% nb1 nb3))
     (data-tests-check-sign (mod -1 -3) (mod nb1 nb3))))
 
+(ert-deftest data-tests-bignum-remainder-invariants ()
+  (let* ((b (1+ most-positive-fixnum))
+         (d 7)
+         (r (mod b d)))
+    (should (= b (+ (* d (floor (/ b d))) r)))
+    (should (<= 0 r))
+    (should (< r (abs d))))
+  (let* ((b (- (1+ most-positive-fixnum)))
+         (d 7)
+         (q (/ b d))
+         (r (% b d)))
+    (should (= b (+ (* q d) r)))
+    (should (<= r 0))
+    (should (> r (- (abs d))))))
+
 (ert-deftest data-tests-mod-0 ()
   (dolist (num (list (1- most-negative-fixnum) -1 0 1
                      (1+ most-positive-fixnum)))
diff --git a/test/src/editfns-tests.el b/test/src/editfns-tests.el
index 0f5e0adc419..785429603ef 100644
--- a/test/src/editfns-tests.el
+++ b/test/src/editfns-tests.el
@@ -132,6 +132,47 @@
   "Number of args for `propertize' must be odd."
   (should-error (propertize "foo" 'bar) :type 'wrong-number-of-arguments))
 
+(ert-deftest editfns-tests--line-boundaries ()
+  (with-temp-buffer
+    (insert "ab\ncd\n")
+    (goto-char (point-min))
+    (should (bobp))
+    (should (bolp))
+    (should-not (eobp))
+    (should (= (line-beginning-position) (point-min)))
+    (should (= (line-end-position) 3))
+    (forward-char 1)
+    (should-not (bolp))
+    (should-not (eolp))
+    (goto-char (line-end-position))
+    (should (eolp))
+    (forward-char 1)
+    (should (bolp))
+    (goto-char (point-max))
+    (should (eobp))
+    (should-not (bobp))))
+
+(ert-deftest editfns-tests--current-column-move-to-column ()
+  (with-temp-buffer
+    (insert "ab  cd\n")
+    (goto-char (point-min))
+    (should (= (current-column) 0))
+    (move-to-column 4)
+    (should (= (current-column) 4))
+    (should (= (point) (+ (point-min) 4)))))
+
+(ert-deftest editfns-tests--pos-bol-eol ()
+  (with-temp-buffer
+    (insert "ab\ncde\nf")
+    (goto-char (point-min))
+    (forward-char 1)
+    (should (= (pos-bol) (point-min)))
+    (should (= (pos-eol) 3))
+    (should (= (pos-bol 2) 4))
+    (should (= (pos-eol 2) 7))
+    (should (= (pos-bol 3) 8))
+    (should (= (pos-eol 3) 9))))
+
 ;; Tests for bug#5131.
 (defun transpose-test-reverse-word (start end)
   "Reverse characters in a word by transposing pairs of characters."
diff --git a/test/src/marker-tests.el b/test/src/marker-tests.el
index 4311a82693b..83d98107a99 100644
--- a/test/src/marker-tests.el
+++ b/test/src/marker-tests.el
@@ -69,6 +69,27 @@
       (should (= (marker-position m1) 2))
       (should (= (marker-position m2) 3)))))
 
+(ert-deftest marker-tests--set-marker-insertion-type ()
+  (with-temp-buffer
+    (insert "ab")
+    (goto-char 2)
+    (let ((m (point-marker)))
+      (should-not (marker-insertion-type m))
+      (should (eq (set-marker-insertion-type m t) t))
+      (should (marker-insertion-type m))
+      (insert "X")
+      (should (= (marker-position m) 3))
+      (goto-char (marker-position m))
+      (should (eq (set-marker-insertion-type m nil) nil))
+      (should-not (marker-insertion-type m))
+      (insert "Y")
+      (should (= (marker-position m) 3)))))
+
+(ert-deftest marker-tests--copy-marker-nil ()
+  (let ((m (copy-marker nil)))
+    (should-not (marker-buffer m))
+    (should-not (marker-position m))))
+
 (ert-deftest marker-tests--last-position-after-kill ()
   (let (marker pos)
     (with-temp-buffer