tests: rework handling of temp output files

Many of the tests open files in local paths for writing which leaves a
variety of temp files in the tests subdirs.  This ends up failing in a
few scenarios like out of tree builds or cmake builds.

Add a few helper functions to the common gdtest module to quickly get
handles to temp files for the tests to leverage.

1 files changed, 3 insertions, 7 deletions

diff --git a/tests/png/png_im2im.c b/tests/png/png_im2im.c
index bac5e13..df6037d 100644
--- a/tests/png/png_im2im.c
+++ b/tests/png/png_im2im.c
@@ -23,13 +23,9 @@ int main()
 	gdImageEllipse(src, 70, 25, 30, 20, b);
 
 #define OUTPUT_PNG(name) do {							\
-		FILE *fp;										\
-														\
-		fp = fopen("png_im2im_" #name ".png", "wb");	\
-		if (fp) {										\
-			gdImagePng(name, fp);						\
-			fclose(fp);									\
-		}												\
+		FILE *fp = gdTestTempFp();						\
+		gdImagePng(name, fp);							\
+		fclose(fp);										\
 	} while (0)
 
 	OUTPUT_PNG(src);