Add test data "artifact_manifest.json" from specification example

Example is copied from https://github.com/opencontainers/image-spec/blob/4df8887994e871a59f9e30e8dd811d060f6a39ef/artifact.md

Signed-off-by: Toshiki Teramura <toshiki.teramura@gmail.com>

src/image/artifact.rs

@@ -213,3 +213,63 @@ impl ArtifactManifest {
     }
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use crate::image::DescriptorBuilder;
+    use std::path::PathBuf;
+
+    fn get_manifest_path() -> PathBuf {
+        PathBuf::from(env!("CARGO_MANIFEST_DIR")).join("test/data/artifact_manifest.json")
+    }
+
+    fn create_manifest() -> ArtifactManifest {
+        let blob = DescriptorBuilder::default()
+            .media_type(MediaType::Other("application/gzip".to_string()))
+            .size(123)
+            .digest(
+                "sha256:87923725d74f4bfb94c9e86d64170f7521aad8221a5de834851470ca142da630"
+                    .to_string(),
+            )
+            .build()
+            .unwrap();
+        let subject = DescriptorBuilder::default()
+            .media_type(MediaType::ImageManifest)
+            .size(1234)
+            .digest(
+                "sha256:cc06a2839488b8bd2a2b99dcdc03d5cfd818eed72ad08ef3cc197aac64c0d0a0"
+                    .to_string(),
+            )
+            .build()
+            .unwrap();
+        let annotations = HashMap::from([
+            (
+                "org.opencontainers.artifact.created".to_string(),
+                "2022-01-01T14:42:55Z".to_string(),
+            ),
+            ("org.example.sbom.format".to_string(), "json".to_string()),
+        ]);
+        ArtifactManifestBuilder::default()
+            .artifact_type(MediaType::Other(
+                "application/vnd.example.sbom.v1".to_string(),
+            ))
+            .blobs(vec![blob])
+            .subject(subject)
+            .annotations(annotations)
+            .build()
+            .unwrap()
+    }
+
+    #[test]
+    fn load_manifest_from_file() {
+        // arrange
+        let manifest_path = get_manifest_path();
+        let expected = create_manifest();
+
+        // act
+        let actual = ArtifactManifest::from_file(manifest_path).expect("from file");
+
+        // assert
+        assert_eq!(actual, expected);
+    }
+}

test/data/artifact_manifest.json

@@ -0,0 +1,20 @@
+{
+  "mediaType": "application/vnd.oci.artifact.manifest.v1+json",
+  "artifactType": "application/vnd.example.sbom.v1",
+  "blobs": [
+    {
+      "mediaType": "application/gzip",
+      "size": 123,
+      "digest": "sha256:87923725d74f4bfb94c9e86d64170f7521aad8221a5de834851470ca142da630"
+    }
+  ],
+  "subject": {
+    "mediaType": "application/vnd.oci.image.manifest.v1+json",
+    "size": 1234,
+    "digest": "sha256:cc06a2839488b8bd2a2b99dcdc03d5cfd818eed72ad08ef3cc197aac64c0d0a0"
+  },
+  "annotations": {
+    "org.opencontainers.artifact.created": "2022-01-01T14:42:55Z",
+    "org.example.sbom.format": "json"
+  }
+}