diff --git a/testing/lisp/test-ob.el b/testing/lisp/test-ob.el
index c8dbd44f4..de92cb90b 100644
--- a/testing/lisp/test-ob.el
+++ b/testing/lisp/test-ob.el
@@ -314,6 +314,147 @@ (ert-deftest test-ob/parse-header-args2 ()
     (org-babel-next-src-block)
     (should (= 14 (org-babel-execute-src-block)))))
 
+(defun test-ob/get-src-block-property (properties)
+  "Get plist of PROPERTIES and values for the first src block in buffer.
+PROPERTIES is a list of property keywords or a single keyword."
+  (org-with-wide-buffer
+   (goto-char (point-min))
+   (org-babel-next-src-block)
+   (org-set-regexps-and-options)
+   (let ((all-props (nth 2 (org-babel-get-src-block-info))))
+     (if (listp properties)
+         (apply #'nconc (mapcar (lambda (p) (list p (cdr (assoc p all-props)))) properties))
+       (list properties (cdr (assoc properties all-props)))))))
+
+(ert-deftest test-ob/merge-params ()
+  "Test the output of merging multiple header parameters.  The
+expected output is given in the contents of the source code block
+in each test.  The desired test header parameters are given
+either as a symbol or a list in the `idtest-alist' variable.
+Multiple header parameters must be separated by a newline and
+exactly two spaces in the block contents."
+  (should ;; 1. inherit-document-header-args
+   (equal '(:tangle "/tmp/default_tangle.txt")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+#+begin_src conf
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should  ;; 2. inherit-document-header-with-local-sync-action
+   (equal '(:tangle "/tmp/default_tangle.txt skip")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+#+begin_src conf :tangle skip
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should ;; 3. override-document-header-with-local-tfile
+   (equal '(:tangle "randomfile sync")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+#+begin_src conf :tangle randomfile sync
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should  ;; 4. override-document-and-parent-header-with-local-tfile-and-action
+   (equal '(:tangle "randomfile sync")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+:PROPERTIES:
+:header-args: :tangle \"newfile.txt\" import
+:END:
+** Two
+#+begin_src conf :tangle randomfile sync
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should ;; 5. test-tangle-and-default-results-param-together
+   (equal '(:tangle "randomfile" :results "replace")
+          (org-test-with-temp-text
+              "\
+* One
+#+begin_src conf  :tangle randomfile
+#+end_src"
+            (test-ob/get-src-block-property '(:tangle :results)))))
+  (should  ;; 6. inherit-document-tfile-take-only-last-local-sync-action
+   (equal '(:tangle "/tmp/default_tangle.txt export")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+#+begin_src conf  :tangle import export
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should  ;; 7. ignore-document-header-take-last-tfile-and-sync-action
+   (equal '(:tangle "fname2 export")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+#+begin_src conf  :tangle fname1 fname2 sync export
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should  ;; 8. test-results-and-exports
+   (equal '(:results "wrap file replace" :exports "code")
+          (org-test-with-temp-text
+              "\
+* One
+#+begin_src sh :results file wrap
+#+end_src"
+            (test-ob/get-src-block-property '(:results :exports)))))
+  (should-not  ;; 9. do-not-tangle-this-block --
+   (equal '(:tangle "no")
+          ;; THIS SHOULD NOT FAIL WITH NEW MERGE FUNCTION.
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+#+begin_src conf :tangle no
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should  ;; 10. test-tangle-exports-and-comments
+   (equal '(:tangle "foo.txt" :exports "verbatim code" :comments "link")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+:PROPERTIES:
+:header-args: :tangle no :exports verbatim
+:END:
+#+begin_src conf :tangle \"foo.txt\" :comments link
+#+end_src"
+            (test-ob/get-src-block-property '(:tangle :exports :comments)))))
+  (should  ;; 11. override-document-and-heading-tfile-with-yes
+   (equal '(:tangle "foo.txt")
+          (org-test-with-temp-text
+              "\
+#+PROPERTY: header-args :tangle /tmp/default_tangle.txt
+* One
+:PROPERTIES:
+:header-args: :tangle \"foo.txt\"
+:END:
+#+begin_src conf :tangle yes
+#+end_src"
+            (test-ob/get-src-block-property :tangle))))
+  (should-not  ;; 12. tangle-file-with-spaces
+   ;; THIS SHOULD NOT FAIL WITH NEW MERGE FUNCTION.
+   (equal '(:tangle "file with spaces.txt")
+          (org-test-with-temp-text
+              "\
+* One
+:PROPERTIES:
+:header-args: :tangle \"foo.txt\"
+:END:
+** Two
+#+begin_src conf :tangle \"file with spaces.txt\"
+#+end_src"
+            (test-ob/get-src-block-property :tangle)))))
+
 (ert-deftest test-ob/inline-src-blocks ()
   (should
    (= 1