test(docx): add PNG fallback generation test for SVG

Just look at --trace output.
Can't use a golden test because the actual .png will be different
depending on rsvg-convert version.

Signed-off-by: Edwin Török <[email protected]>

Author: edwintorok

test/command/9288.md

@@ -0,0 +1,52 @@
+```
+% pandoc -f native -t docx -o 9288.docx  --trace
+[ Figure
+    ( "" , [] , [] )
+    (Caption Nothing [ Plain [ Str "5in" ] ])
+    [ Plain
+        [ Image
+            ( "" , [] , [ ( "width" , "5in" ) ] )
+            [ Str "5in" ]
+            ( "command/SVG_logo.svg" , "" )
+        ]
+    ]
+, Figure
+    ( "" , [] , [] )
+    (Caption Nothing [ Plain [ Str "5in" ] ])
+    [ Plain
+        [ Image
+            ( "" , [] , [ ( "width" , "5in" ) ] )
+            [ Str "5in" ]
+            ( "command/SVG_logo.svg" , "" )
+        ]
+    ]
+, Figure
+    ( "" , [] , [] )
+    (Caption Nothing [ Plain [ Str "80%" ] ])
+    [ Plain
+        [ Image
+            ( "" , [] , [ ( "width" , "80%" ) ] )
+            [ Str "5in" ]
+            ( "command/SVG_logo.svg" , "" )
+        ]
+    ]
+, Figure
+    ( "" , [] , [] )
+    (Caption Nothing [ Plain [ Str "default" ] ])
+    [ Plain
+        [ Image
+            ( "" , [] , [] )
+            [ Str "5in" ]
+            ( "command/SVG_logo.svg" , "" )
+        ]
+    ]
+]
+^D
+2> [trace] rsvg-convert -f png -a --dpi-x 96 --dpi-y 96 --width 360.000000pt --height 360.000000pt
+2> [trace] Found fallback "media/rId20.svg_4572000_4572000.png"
+2> [trace] Found fallback "media/rId20.svg_4572000_4572000.png"
+2> [trace] rsvg-convert -f png -a --dpi-x 96 --dpi-y 96 --width 75.000000pt --height 75.000000pt
+2> [trace] Found fallback "media/rId20.svg_952500_952500.png"
+2> [trace] Found fallback "media/rId20.svg_952500_952500.png"
+
+```