[librsvg: 1/3] SvgPredicate: make eval() actually test if some bytes are an SVG document

[Marge Bot <marge-bot src gnome org>]

commit f3d7df9229f9db777bff7ef9fbba3f3ecd18bc6d
Author: Federico Mena Quintero <federico gnome org>
Date:   Tue Dec 7 15:07:46 2021 -0600

    SvgPredicate: make eval() actually test if some bytes are an SVG document
    
    It was just validating the bytes as UTF-8.
    
    Part-of: <https://gitlab.gnome.org/GNOME/librsvg/-/merge_requests/640>

 tests/src/cmdline/rsvg_convert.rs |  2 +-
 tests/src/predicates/svg.rs       | 22 ++++++++++------------
 2 files changed, 11 insertions(+), 13 deletions(-)
---
diff --git a/tests/src/cmdline/rsvg_convert.rs b/tests/src/cmdline/rsvg_convert.rs
index 877d8214..3e62140d 100644
--- a/tests/src/cmdline/rsvg_convert.rs
+++ b/tests/src/cmdline/rsvg_convert.rs
@@ -153,7 +153,7 @@ fn output_format_svg_short_option() {
         .arg("svg")
         .assert()
         .success()
-        .stdout(file::is_svg().with_svg_format());
+        .stdout(file::is_svg());
 }
 
 #[cfg(system_deps_have_cairo_svg)]
diff --git a/tests/src/predicates/svg.rs b/tests/src/predicates/svg.rs
index f9409126..40412204 100644
--- a/tests/src/predicates/svg.rs
+++ b/tests/src/predicates/svg.rs
@@ -1,9 +1,7 @@
-use librsvg::Length;
-use predicates::boolean::AndPredicate;
+use gio::MemoryInputStream;
+use glib::Bytes;
 use predicates::prelude::*;
 use predicates::reflection::{Case, Child, PredicateReflection, Product};
-use predicates::str::StartsWithPredicate;
-use predicates::str::*;
 use std::cmp;
 use std::fmt;
 use std::str;
@@ -13,7 +11,7 @@ use libxml::xpath::Context;
 
 use librsvg::doctest_only::Both;
 use librsvg::rsvg_convert_only::ULength;
-use librsvg::Parse;
+use librsvg::{Length, Loader, LoadingError, Parse, SvgHandle};
 
 /// Checks that the variable of type [u8] can be parsed as a SVG file.
 #[derive(Debug)]
@@ -29,21 +27,21 @@ impl SvgPredicate {
             }),
         }
     }
+}
 
-    pub fn with_svg_format(
-        self: Self,
-    ) -> AndPredicate<StartsWithPredicate, ContainsPredicate, str> {
-        predicate::str::starts_with("<?xml ").and(predicate::str::contains("<svg "))
-    }
+fn svg_from_bytes(data: &[u8]) -> Result<SvgHandle, LoadingError> {
+    let bytes = Bytes::from(data);
+    let stream = MemoryInputStream::from_bytes(&bytes);
+    Loader::new().read_stream(&stream, None::<&gio::File>, None::<&gio::Cancellable>)
 }
 
 impl Predicate<[u8]> for SvgPredicate {
     fn eval(&self, data: &[u8]) -> bool {
-        str::from_utf8(data).is_ok()
+        svg_from_bytes(data).is_ok()
     }
 
     fn find_case<'a>(&'a self, _expected: bool, data: &[u8]) -> Option<Case<'a>> {
-        match str::from_utf8(data) {
+        match svg_from_bytes(data) {
             Ok(_) => None,
             Err(e) => Some(Case::new(Some(self), false).add_product(Product::new("Error", e))),
         }