From ca93f39201f6f8be9bc1466eed7323d0426e135c Mon Sep 17 00:00:00 2001
From: Nadrieril
Date: Sun, 9 Feb 2020 15:50:58 +0000
Subject: Track output of import errors

---
 dhall/build.rs                               | 16 ++++++++++++++++
 dhall/src/tests.rs                           | 26 ++++++++++++++++++++++++++
 dhall/tests/errors/import/cycle.txt          |  1 +
 dhall/tests/errors/import/importBoundary.txt |  1 +
 4 files changed, 44 insertions(+)
 create mode 100644 dhall/tests/errors/import/cycle.txt
 create mode 100644 dhall/tests/errors/import/importBoundary.txt

diff --git a/dhall/build.rs b/dhall/build.rs
index 83c154e..7733581 100644
--- a/dhall/build.rs
+++ b/dhall/build.rs
@@ -245,6 +245,22 @@ fn generate_tests() -> std::io::Result<()> {
             input_type: FileType::Text,
             output_type: None,
         },
+        TestFeature {
+            module_name: "import_error",
+            directory: "import/failure/",
+            variant: "ImportError",
+            path_filter: Box::new(|path: &str| {
+                false
+                    || path == "alternativeEnv"
+                    || path == "alternativeEnvMissing"
+                    || path == "hashMismatch"
+                    || path == "missing"
+                    || path == "referentiallyInsane"
+                    || path == "customHeadersUsingBoundVariable"
+            }),
+            input_type: FileType::Text,
+            output_type: None,
+        },
         TestFeature {
             module_name: "beta_normalize",
             directory: "normalization/success/",
diff --git a/dhall/src/tests.rs b/dhall/src/tests.rs
index 8136625..449e7ee 100644
--- a/dhall/src/tests.rs
+++ b/dhall/src/tests.rs
@@ -61,6 +61,7 @@ pub enum Test<'a> {
     BinaryDecodingFailure(&'a str),
     ImportSuccess(&'a str, &'a str),
     ImportFailure(&'a str),
+    ImportError(&'a str),
     TypeInferenceSuccess(&'a str, &'a str),
     TypeInferenceFailure(&'a str),
     TypeError(&'a str),
@@ -157,6 +158,31 @@ pub fn run_test(test: Test<'_>) -> Result<()> {
         ImportFailure(file_path) => {
             parse_file_str(&file_path)?.resolve().unwrap_err();
         }
+        // Checks the output of the type error against a text file. If the text file doesn't exist,
+        // we instead write to it the output we got. This makes it easy to update those files: just
+        // `rm -r dhall/tests/type-errors` and run the tests again.
+        ImportError(file_path) => {
+            let err: Error =
+                parse_file_str(&file_path)?.resolve().unwrap_err().into();
+            let file_path = PathBuf::from(file_path);
+            let error_file_path = file_path
+                .strip_prefix("../dhall-lang/tests/import/failure/")
+                .or_else(|_| file_path.strip_prefix("tests/import/failure/"))
+                .unwrap();
+            let error_file_path =
+                PathBuf::from("tests/errors/import/").join(error_file_path);
+            let error_file_path = error_file_path.with_extension("txt");
+
+            if error_file_path.is_file() {
+                let expected_msg = std::fs::read_to_string(error_file_path)?;
+                let msg = format!("{}\n", err);
+                assert_eq_pretty_str!(msg, expected_msg);
+            } else {
+                std::fs::create_dir_all(error_file_path.parent().unwrap())?;
+                let mut file = File::create(error_file_path)?;
+                writeln!(file, "{}", err)?;
+            }
+        }
         TypeInferenceSuccess(expr_file_path, expected_file_path) => {
             let expr =
                 parse_file_str(&expr_file_path)?.resolve()?.typecheck()?;
diff --git a/dhall/tests/errors/import/cycle.txt b/dhall/tests/errors/import/cycle.txt
new file mode 100644
index 0000000..0a20503
--- /dev/null
+++ b/dhall/tests/errors/import/cycle.txt
@@ -0,0 +1 @@
+Recursive(Import { mode: Code, location: Local(Parent, FilePath { file_path: ["data", "cycle.dhall"] }), hash: None }, Resolve(Recursive(Import { mode: Code, location: Local(Parent, FilePath { file_path: ["failure", "cycle.dhall"] }), hash: None }, Resolve(ImportCycle([Import { mode: Code, location: Local(Parent, FilePath { file_path: ["data", "cycle.dhall"] }), hash: None }, Import { mode: Code, location: Local(Parent, FilePath { file_path: ["failure", "cycle.dhall"] }), hash: None }], Import { mode: Code, location: Local(Parent, FilePath { file_path: ["data", "cycle.dhall"] }), hash: None })))))
diff --git a/dhall/tests/errors/import/importBoundary.txt b/dhall/tests/errors/import/importBoundary.txt
new file mode 100644
index 0000000..8f78e48
--- /dev/null
+++ b/dhall/tests/errors/import/importBoundary.txt
@@ -0,0 +1 @@
+Recursive(Import { mode: Code, location: Local(Parent, FilePath { file_path: ["data", "importBoundary.dhall"] }), hash: None }, Typecheck(TypeError { message: Custom("error: unbound variable `x`\n --> <current file>:1:0\n  |\n...\n3 | x\n  | ^ not found in this scope\n  |") }))
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