[librsvg: 2/5] New test_utils module in rsvg_internals

[Federico Mena Quintero <federico src gnome org>]

commit beee25fd435abe48f4379ac9c55124263b169596
Author: Federico Mena Quintero <federico gnome org>
Date:   Fri Oct 23 19:28:09 2020 -0500

    New test_utils module in rsvg_internals
    
    Move the generic test utilities from librsvg_crate to here.

 Makefile.am                                        |   1 +
 librsvg_crate/tests/standalone/api.rs              |   3 +-
 librsvg_crate/tests/standalone/bugs.rs             |   3 +-
 .../tests/standalone/intrinsic_dimensions.rs       |   3 +-
 librsvg_crate/tests/standalone/primitives.rs       |   3 +-
 librsvg_crate/tests/standalone/utils.rs            | 102 ---------------------
 rsvg_internals/Cargo.toml                          |   2 +-
 rsvg_internals/src/lib.rs                          |   1 +
 rsvg_internals/src/test_utils.rs                   | 101 ++++++++++++++++++++
 9 files changed, 112 insertions(+), 107 deletions(-)
---
diff --git a/Makefile.am b/Makefile.am
index 814c6b9d..7c5e8cfa 100644
--- a/Makefile.am
+++ b/Makefile.am
@@ -98,6 +98,7 @@ LIBRSVG_INTERNALS_SRC =                                               \
        rsvg_internals/src/space.rs                             \
        rsvg_internals/src/structure.rs                         \
        rsvg_internals/src/style.rs                             \
+       rsvg_internals/src/test_utils.rs                        \
        rsvg_internals/src/text.rs                              \
        rsvg_internals/src/transform.rs                         \
        rsvg_internals/src/unit_interval.rs                     \
diff --git a/librsvg_crate/tests/standalone/api.rs b/librsvg_crate/tests/standalone/api.rs
index 256e6813..ed7d4ee1 100644
--- a/librsvg_crate/tests/standalone/api.rs
+++ b/librsvg_crate/tests/standalone/api.rs
@@ -2,8 +2,9 @@ use cairo;
 use librsvg::{CairoRenderer, DefsLookupErrorKind, HrefError, RenderingError};
 
 use rsvg_internals::surface_utils::shared_surface::{SharedImageSurface, SurfaceType};
+use rsvg_internals::test_utils::compare_to_surface;
 
-use crate::utils::{compare_to_surface, load_svg};
+use crate::utils::load_svg;
 
 #[test]
 fn has_element_with_id_works() {
diff --git a/librsvg_crate/tests/standalone/bugs.rs b/librsvg_crate/tests/standalone/bugs.rs
index 1debc7e6..d07085cd 100644
--- a/librsvg_crate/tests/standalone/bugs.rs
+++ b/librsvg_crate/tests/standalone/bugs.rs
@@ -2,8 +2,9 @@ use cairo;
 use librsvg::{LoadingError, SvgHandle};
 use matches::matches;
 use rsvg_internals::surface_utils::shared_surface::{SharedImageSurface, SurfaceType};
+use rsvg_internals::test_utils::compare_to_surface;
 
-use crate::utils::{compare_to_surface, load_svg, render_document, SurfaceSize};
+use crate::utils::{load_svg, render_document, SurfaceSize};
 
 // https://gitlab.gnome.org/GNOME/librsvg/issues/335
 #[test]
diff --git a/librsvg_crate/tests/standalone/intrinsic_dimensions.rs 
b/librsvg_crate/tests/standalone/intrinsic_dimensions.rs
index 85ed952d..aa8a50b2 100644
--- a/librsvg_crate/tests/standalone/intrinsic_dimensions.rs
+++ b/librsvg_crate/tests/standalone/intrinsic_dimensions.rs
@@ -1,13 +1,14 @@
 use cairo;
 
 use rsvg_internals::surface_utils::shared_surface::{SharedImageSurface, SurfaceType};
+use rsvg_internals::test_utils::compare_to_surface;
 
 use librsvg::{
     CairoRenderer, DefsLookupErrorKind, HrefError, IntrinsicDimensions, Length, LengthUnit,
     RenderingError,
 };
 
-use crate::utils::{compare_to_surface, load_svg, render_document, SurfaceSize};
+use crate::utils::{load_svg, render_document, SurfaceSize};
 
 #[test]
 fn no_intrinsic_dimensions() {
diff --git a/librsvg_crate/tests/standalone/primitives.rs b/librsvg_crate/tests/standalone/primitives.rs
index d9959dad..6d035e45 100644
--- a/librsvg_crate/tests/standalone/primitives.rs
+++ b/librsvg_crate/tests/standalone/primitives.rs
@@ -1,8 +1,9 @@
 use cairo;
 
 use rsvg_internals::surface_utils::shared_surface::{SharedImageSurface, SurfaceType};
+use rsvg_internals::test_utils::compare_to_surface;
 
-use crate::utils::{compare_to_surface, load_svg, render_document, SurfaceSize};
+use crate::utils::{load_svg, render_document, SurfaceSize};
 
 #[test]
 fn simple_opacity_with_transform() {
diff --git a/librsvg_crate/tests/standalone/utils.rs b/librsvg_crate/tests/standalone/utils.rs
index 30776189..ec2df9fe 100644
--- a/librsvg_crate/tests/standalone/utils.rs
+++ b/librsvg_crate/tests/standalone/utils.rs
@@ -7,15 +7,6 @@ use librsvg::{CairoRenderer, Loader, LoadingError, RenderingError, SvgHandle};
 
 use rsvg_internals::surface_utils::shared_surface::{SharedImageSurface, SurfaceType};
 
-use rsvg_internals::{compare_surfaces, BufferDiff, Diff};
-
-use std::convert::TryFrom;
-use std::env;
-use std::fs::{self, File};
-use std::io::BufReader;
-use std::path::PathBuf;
-use std::sync::Once;
-
 pub fn load_svg(input: &'static [u8]) -> Result<SvgHandle, LoadingError> {
     let bytes = glib::Bytes::from_static(input);
     let stream = gio::MemoryInputStream::new_from_bytes(&bytes);
@@ -46,96 +37,3 @@ pub fn render_document<F: FnOnce(&cairo::Context)>(
 
     res.and_then(|_| Ok(SharedImageSurface::wrap(output, SurfaceType::SRgb)?))
 }
-
-fn tolerable_difference() -> u8 {
-    static mut TOLERANCE: u8 = 2;
-
-    static ONCE: Once = Once::new();
-    ONCE.call_once(|| unsafe {
-        if let Ok(str) = env::var("RSVG_TEST_TOLERANCE") {
-            let value: usize = str
-                .parse()
-                .expect("Can not parse RSVG_TEST_TOLERANCE as a number");
-            TOLERANCE =
-                u8::try_from(value).expect("RSVG_TEST_TOLERANCE should be between 0 and 255");
-        }
-    });
-
-    unsafe { TOLERANCE }
-}
-
-trait Deviation {
-    fn distinguishable(&self) -> bool;
-    fn inacceptable(&self) -> bool;
-}
-
-impl Deviation for Diff {
-    fn distinguishable(&self) -> bool {
-        self.max_diff > 2
-    }
-
-    fn inacceptable(&self) -> bool {
-        self.max_diff > tolerable_difference()
-    }
-}
-
-pub fn output_dir() -> PathBuf {
-    let path = PathBuf::from(
-        env::var_os("OUT_DIR")
-            .expect(r#"OUT_DIR is not set, please set it or run under "cargo test""#),
-    );
-
-    fs::create_dir_all(&path).expect("could not create output directory for tests");
-
-    path
-}
-
-pub fn compare_to_surface(
-    output_surf: &SharedImageSurface,
-    reference_surf: &SharedImageSurface,
-    output_base_name: &str,
-) {
-    let output_path = output_dir().join(&format!("{}-out.png", output_base_name));
-
-    println!("output: {}", output_path.to_string_lossy());
-
-    let mut output_file = File::create(output_path).unwrap();
-    output_surf
-        .clone()
-        .into_image_surface()
-        .unwrap()
-        .write_to_png(&mut output_file)
-        .unwrap();
-
-    let diff = compare_surfaces(output_surf, reference_surf).unwrap();
-    evaluate_diff(&diff, output_base_name);
-}
-
-fn evaluate_diff(diff: &BufferDiff, output_base_name: &str) {
-    match diff {
-        BufferDiff::DifferentSizes => unreachable!("surfaces should be of the same size"),
-
-        BufferDiff::Diff(diff) => {
-            if diff.distinguishable() {
-                println!(
-                    "{}: {} pixels changed with maximum difference of {}",
-                    output_base_name, diff.num_pixels_changed, diff.max_diff,
-                );
-                save_diff(diff, output_base_name);
-
-                if diff.inacceptable() {
-                    panic!("surfaces are too different");
-                }
-            }
-        }
-    }
-
-    fn save_diff(diff: &Diff, output_base_name: &str) {
-        let surf = diff.surface.clone().into_image_surface().unwrap();
-        let diff_path = output_dir().join(&format!("{}-diff.png", output_base_name));
-        println!("diff: {}", diff_path.to_string_lossy());
-
-        let mut output_file = File::create(diff_path).unwrap();
-        surf.write_to_png(&mut output_file).unwrap();
-    }
-}
diff --git a/rsvg_internals/Cargo.toml b/rsvg_internals/Cargo.toml
index 27f947b9..e6d90e6c 100644
--- a/rsvg_internals/Cargo.toml
+++ b/rsvg_internals/Cargo.toml
@@ -10,7 +10,7 @@ edition = "2018"
 # Keep these in sync with respect to the cairo-rs version:
 #   librsvg_crate/Cargo.toml
 #   librsvg_crate/src/lib.rs - toplevel example in the docs
-cairo-rs = { version="0.8.0", features=["v1_16"] }
+cairo-rs = { version = "0.8.0", features = ["v1_16", "png", "pdf", "svg"] }
 cairo-sys-rs = "0.9.0"
 cast = "0.2.3"
 cssparser = "0.27.1"
diff --git a/rsvg_internals/src/lib.rs b/rsvg_internals/src/lib.rs
index e43835bd..2eaa88b3 100644
--- a/rsvg_internals/src/lib.rs
+++ b/rsvg_internals/src/lib.rs
@@ -141,6 +141,7 @@ mod space;
 mod structure;
 mod style;
 pub mod surface_utils;
+pub mod test_utils;
 mod text;
 mod transform;
 mod unit_interval;
diff --git a/rsvg_internals/src/test_utils.rs b/rsvg_internals/src/test_utils.rs
new file mode 100644
index 00000000..d47dc730
--- /dev/null
+++ b/rsvg_internals/src/test_utils.rs
@@ -0,0 +1,101 @@
+use crate::surface_utils::shared_surface::SharedImageSurface;
+use crate::surface_utils::compare_surfaces::{compare_surfaces, BufferDiff, Diff};
+
+use std::convert::TryFrom;
+use std::env;
+use std::fs::{self, File};
+use std::path::PathBuf;
+use std::sync::Once;
+
+fn tolerable_difference() -> u8 {
+    static mut TOLERANCE: u8 = 2;
+
+    static ONCE: Once = Once::new();
+    ONCE.call_once(|| unsafe {
+        if let Ok(str) = env::var("RSVG_TEST_TOLERANCE") {
+            let value: usize = str
+                .parse()
+                .expect("Can not parse RSVG_TEST_TOLERANCE as a number");
+            TOLERANCE =
+                u8::try_from(value).expect("RSVG_TEST_TOLERANCE should be between 0 and 255");
+        }
+    });
+
+    unsafe { TOLERANCE }
+}
+
+trait Deviation {
+    fn distinguishable(&self) -> bool;
+    fn inacceptable(&self) -> bool;
+}
+
+impl Deviation for Diff {
+    fn distinguishable(&self) -> bool {
+        self.max_diff > 2
+    }
+
+    fn inacceptable(&self) -> bool {
+        self.max_diff > tolerable_difference()
+    }
+}
+
+pub fn output_dir() -> PathBuf {
+    let path = PathBuf::from(
+        env::var_os("OUT_DIR")
+            .expect(r#"OUT_DIR is not set, please set it or run under "cargo test""#),
+    );
+
+    fs::create_dir_all(&path).expect("could not create output directory for tests");
+
+    path
+}
+
+pub fn compare_to_surface(
+    output_surf: &SharedImageSurface,
+    reference_surf: &SharedImageSurface,
+    output_base_name: &str,
+) {
+    let output_path = output_dir().join(&format!("{}-out.png", output_base_name));
+
+    println!("output: {}", output_path.to_string_lossy());
+
+    let mut output_file = File::create(output_path).unwrap();
+    output_surf
+        .clone()
+        .into_image_surface()
+        .unwrap()
+        .write_to_png(&mut output_file)
+        .unwrap();
+
+    let diff = compare_surfaces(output_surf, reference_surf).unwrap();
+    evaluate_diff(&diff, output_base_name);
+}
+
+fn evaluate_diff(diff: &BufferDiff, output_base_name: &str) {
+    match diff {
+        BufferDiff::DifferentSizes => unreachable!("surfaces should be of the same size"),
+
+        BufferDiff::Diff(diff) => {
+            if diff.distinguishable() {
+                println!(
+                    "{}: {} pixels changed with maximum difference of {}",
+                    output_base_name, diff.num_pixels_changed, diff.max_diff,
+                );
+                save_diff(diff, output_base_name);
+
+                if diff.inacceptable() {
+                    panic!("surfaces are too different");
+                }
+            }
+        }
+    }
+
+    fn save_diff(diff: &Diff, output_base_name: &str) {
+        let surf = diff.surface.clone().into_image_surface().unwrap();
+        let diff_path = output_dir().join(&format!("{}-diff.png", output_base_name));
+        println!("diff: {}", diff_path.to_string_lossy());
+
+        let mut output_file = File::create(diff_path).unwrap();
+        surf.write_to_png(&mut output_file).unwrap();
+    }
+}