diff --git a/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-001.html b/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-001.html
index 7c6f17886c618..918631014d3b4 100644
--- a/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-001.html
+++ b/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-001.html
@@ -942,6 +942,106 @@
 "
 )
 ;
+test
+(
+function
+(
+)
+{
+assert_true
+(
+MathMLFeatureDetection
+.
+has_operator_spacing
+(
+)
+)
+;
+assert_approx_equals
+(
+spaceBefore
+(
+"
+merror1
+"
+)
+emToPx
+epsilon
+)
+;
+assert_approx_equals
+(
+spaceAfter
+(
+"
+merror1
+"
+)
+emToPx
+epsilon
+)
+;
+}
+"
+space
+-
+like
+merror
+"
+)
+;
+test
+(
+function
+(
+)
+{
+assert_true
+(
+MathMLFeatureDetection
+.
+has_operator_spacing
+(
+)
+)
+;
+assert_approx_equals
+(
+spaceBefore
+(
+"
+merror2
+"
+)
+0
+epsilon
+)
+;
+assert_approx_equals
+(
+spaceAfter
+(
+"
+merror2
+"
+)
+2
+*
+emToPx
+epsilon
+)
+;
+}
+"
+non
+-
+space
+-
+like
+merror
+"
+)
+;
 done
 (
 )
@@ -1902,6 +2002,200 @@
 p
 >
 <
+p
+>
+<
+math
+>
+<
+mn
+>
+X
+<
+/
+mn
+>
+<
+mrow
+>
+<
+merror
+id
+=
+"
+merror1
+"
+class
+=
+"
+testedElement
+"
+>
+<
+mtext
+>
+X
+<
+/
+mtext
+>
+<
+mspace
+width
+=
+"
+25px
+"
+height
+=
+"
+10px
+"
+>
+<
+/
+mspace
+>
+<
+/
+merror
+>
+<
+mo
+lspace
+=
+"
+1em
+"
+rspace
+=
+"
+0em
+"
+>
+X
+<
+/
+mo
+>
+<
+/
+mrow
+>
+<
+mn
+>
+X
+<
+/
+mn
+>
+<
+/
+math
+>
+<
+/
+p
+>
+<
+p
+>
+<
+math
+>
+<
+mn
+>
+X
+<
+/
+mn
+>
+<
+mrow
+>
+<
+merror
+id
+=
+"
+merror2
+"
+class
+=
+"
+testedElement
+"
+>
+<
+mn
+>
+X
+<
+/
+mn
+>
+<
+mspace
+width
+=
+"
+25px
+"
+height
+=
+"
+10px
+"
+>
+<
+/
+mspace
+>
+<
+/
+merror
+>
+<
+mo
+lspace
+=
+"
+1em
+"
+rspace
+=
+"
+0em
+"
+>
+X
+<
+/
+mo
+>
+<
+/
+mrow
+>
+<
+mn
+>
+X
+<
+/
+mn
+>
+<
+/
+math
+>
+<
+/
+p
+>
+<
 /
 body
 >
diff --git a/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-002.html b/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-002.html
index 0ca86f726cf50..6413fbe05fac1 100644
--- a/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-002.html
+++ b/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-002.html
@@ -515,7 +515,7 @@
 maction2
 "
 )
-0
+emToPx
 epsilon
 )
 ;
@@ -527,17 +527,14 @@
 maction2
 "
 )
-2
-*
 emToPx
 epsilon
 )
 ;
 }
 "
-non
--
 space
+-
 like
 maction
 (
@@ -678,7 +675,7 @@
 semantics2
 "
 )
-0
+emToPx
 epsilon
 )
 ;
@@ -690,17 +687,14 @@
 semantics2
 "
 )
-2
-*
 emToPx
 epsilon
 )
 ;
 }
 "
-non
--
 space
+-
 like
 semantics
 (
diff --git a/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-003.html b/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-003.html
index 77e1765421df0..cd7e2c3ca1bb5 100644
--- a/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-003.html
+++ b/testing/web-platform/tests/mathml/presentation-markup/spaces/space-like-003.html
@@ -545,81 +545,6 @@
 mrow
 >
 <
-merror
-class
-=
-"
-testedElement
-"
->
-<
-mtext
->
-X
-<
-/
-mtext
->
-<
-/
-merror
->
-<
-mo
-lspace
-=
-"
-1em
-"
-rspace
-=
-"
-0em
-"
->
-X
-<
-/
-mo
->
-<
-/
-mrow
->
-<
-mn
->
-X
-<
-/
-mn
->
-<
-/
-math
->
-<
-/
-p
->
-<
-p
->
-<
-math
->
-<
-mn
->
-X
-<
-/
-mn
->
-<
-mrow
->
-<
 mroot
 class
 =