3 files changed, 32 insertions, 1 deletions
diff --git a/dhall/Cargo.toml b/dhall/Cargo.toml
index 75d38f1..ae6665e 100644
--- a/dhall/Cargo.toml
+++ b/dhall/Cargo.toml
@@ -22,6 +22,7 @@ pest_consume = "1.0"
 reqwest = { version = "0.10", features = ["blocking"] }
 serde = "1.0"
 serde_cbor = "0.9.0"
+sha2 = "0.8.1"
 smallvec = "1.0.0"
 url = "2.1"
 
diff --git a/dhall/build.rs b/dhall/build.rs
index 19abcc4..c79682d 100644
--- a/dhall/build.rs
+++ b/dhall/build.rs
@@ -14,6 +14,8 @@ enum FileType {
     Text,
     /// Dhall binary file
     Binary,
+    /// Text file with hash
+    Hash,
     /// Text file with expected text output
     UI,
 }
@@ -23,6 +25,7 @@ impl FileType {
         match self {
             FileType::Text => "dhall",
             FileType::Binary => "dhallb",
+            FileType::Hash => "hash",
             FileType::UI => "txt",
         }
     }
@@ -30,6 +33,7 @@ impl FileType {
         match self {
             FileType::Text => "TestFile::Source",
             FileType::Binary => "TestFile::Binary",
+            FileType::Hash => "TestFile::Binary",
             FileType::UI => "TestFile::UI",
         }
     }
@@ -280,6 +284,22 @@ fn generate_tests() -> std::io::Result<()> {
             ..default_feature.clone()
         },
         TestFeature {
+            module_name: "semantic_hash",
+            directory: "semantic-hash/success/",
+            variant: "SemanticHash",
+            exclude_path: Rc::new(|path: &str| {
+                false
+                    // We don't support bignums
+                    || path == "simple/integerToDouble"
+                    // See https://github.com/pyfisch/cbor/issues/109
+                    || path == "prelude/Integer/toDouble/0"
+                    || path == "prelude/Integer/toDouble/1"
+                    || path == "prelude/Natural/toDouble/0"
+            }),
+            output_type: Some(FileType::Hash),
+            ..default_feature.clone()
+        },
+        TestFeature {
             module_name: "beta_normalize",
             directory: "normalization/success/",
             variant: "Normalization",
diff --git a/dhall/src/tests.rs b/dhall/src/tests.rs
index 2cd354f..a194c9a 100644
--- a/dhall/src/tests.rs
+++ b/dhall/src/tests.rs
@@ -63,6 +63,7 @@ enum Test {
     BinaryDecodingFailure(TestFile, TestFile),
     ImportSuccess(TestFile, TestFile),
     ImportFailure(TestFile, TestFile),
+    SemanticHash(TestFile, TestFile),
     TypeInferenceSuccess(TestFile, TestFile),
     TypeInferenceFailure(TestFile, TestFile),
     Normalization(TestFile, TestFile),
@@ -132,7 +133,7 @@ impl TestFile {
     fn write_ui(&self, x: impl Display) -> Result<()> {
         match self {
             TestFile::UI(_) => {}
-            _ => panic!("Can't write an error to a non-UI file"),
+            _ => panic!("Can't write a ui string to a dhall file"),
         }
         let path = self.path();
         create_dir_all(path.parent().unwrap())?;
@@ -302,6 +303,15 @@ fn run_test(test: Test) -> Result<()> {
             let err = expr.resolve().unwrap_err();
             expected.compare_ui(err)?;
         }
+        SemanticHash(expr, expected) => {
+            use sha2::Digest;
+            let expr = expr.normalize()?.to_expr_alpha();
+            dbg!(&expr);
+            let expr_data = binary::encode(&expr)?;
+            let hash = sha2::Sha256::digest(&expr_data);
+            let hash = hex::encode(hash);
+            expected.compare_ui(format!("sha256:{}", hash))?;
+        }
         TypeInferenceSuccess(expr, expected) => {
             let ty = expr.typecheck()?.get_type()?;
             expected.compare(ty)?;