[test] Add a test for "deep" subdir

test/test_compilation/datadir.tex.control

@@ -168,6 +168,33 @@ Chordpro}[
 \image{@TEST_FOLDER@/datadir_datadir/songs/./relative.png}
 
 
+\endsong
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% songs/./subdir/subdir.sg
+
+\import{datadir_datadir/songs/subdir/}{subdir.sg}
+
+%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%
+%% songs/./subdir/subdir.sgc
+
+\selectlanguage{english}
+
+\beginsong{Image included from a nested song directory\\
+Chordpro}[
+  by={
+  },
+    cov={@TEST_FOLDER@/datadir_datadir/songs/./subdir/subdir.png},
+]
+
+\cover
+
+
+
+\lilypond{@TEST_FOLDER@/datadir_datadir/songs/./subdir/subdir.ly}
+\image{@TEST_FOLDER@/datadir_datadir/songs/./subdir/subdir.png}
+
+
 \endsong
 
 \end{songs}

test/test_compilation/datadir_datadir/songs/subdir/subdir.ly

@@ -0,0 +1,19 @@
+\include "_lilypond/header"
+\paper{paper-height = 6.5\cm}
+
+{
+  \key a \minor
+    \time 6/8
+    \partial 8 a'8
+    \relative c''{
+      c4 d8 e8. (f16) e8 d4 b8 g8. (a16) b8
+      c4 a8 a8. (gis16) a8 b4 gis8 e4 a8
+      c4 d8 e8. (f16 e8) d4 b8 g8. (a16) b8
+      c8. (b16) a8 gis8. (fis16) gis8 a4 a8 a4.
+
+      g'4. g8. (fis16) e8 d4 b8 g8. (a16) b8
+      c4 (a8) a8. (gis16) a8 b4 gis8 e4.
+      g'4. g8. (fis16) e8 d4 b8 g8. (a16) b8
+      c8. (b16) a8 gis8. (fis16) gis8 a4. a4.
+    }
+}

test/test_compilation/datadir_datadir/songs/subdir/subdir.sg

@@ -0,0 +1,10 @@
+\beginsong{Image included from a nested song directory\\\LaTeX}
+  [cov={subdir}]
+
+  \cover
+
+  \lilypond{subdir.ly}
+
+  \image{subdir}
+
+\endsong

test/test_compilation/datadir_datadir/songs/subdir/subdir.sgc

@@ -0,0 +1,7 @@
+{title : Image included from a nested song directory}
+{subtitle: Chordpro}
+{cover: subdir.png}
+{lang: en}
+
+{partition: subdir.ly}
+{image: subdir.png}