feat(xatu): report empty let expressions

src/xatu/xatu_test.rs

@@ -113,6 +113,51 @@ fn xatu_reports_empty_inherit() -> googletest::Result<()> {
     Ok(())
 }
 
+#[gtest]
+fn xatu_reports_empty_let_in() -> googletest::Result<()> {
+    let source = fixture_source("testdata/lint_findings.nix")?;
+    let range_start = source.source.find("let in src").or_fail()?;
+    let range_end = range_start + "let in src".len();
+    let report = xatu::future_sight(vec![source]).or_fail()?;
+
+    let finding = report
+        .diagnostics
+        .iter()
+        .map(|diagnostic| &diagnostic.finding)
+        .find(|finding| finding.rule_id == "empty_let_in")
+        .or_fail()?;
+    let expected_range = format!("{range_start}..{range_end}");
+    expect_that!(finding.range.to_string(), eq(&expected_range));
+    Ok(())
+}
+
+#[gtest]
+fn xatu_reports_commented_empty_let_in() -> googletest::Result<()> {
+    let report = xatu::future_sight(vec![fixture_source("testdata/lint_variants.nix")?]).or_fail()?;
+
+    let findings = report
+        .diagnostics
+        .iter()
+        .map(|diagnostic| diagnostic.finding.rule_id)
+        .collect::<Vec<_>>();
+    expect_that!(findings, contains(eq(&"empty_let_in")));
+    Ok(())
+}
+
+#[gtest]
+fn xatu_reports_empty_let_with_empty_inherit() -> googletest::Result<()> {
+    let report =
+        xatu::future_sight(vec![fixture_source("testdata/lint_interactions.nix")?]).or_fail()?;
+
+    let findings = report
+        .diagnostics
+        .iter()
+        .map(|diagnostic| diagnostic.finding.rule_id)
+        .collect::<Vec<_>>();
+    expect_that!(findings, eq(&vec!["empty_let_in", "empty_inherit"]));
+    Ok(())
+}
+
 #[gtest]
 fn xatu_reports_unquoted_uri() -> googletest::Result<()> {
     let report = xatu::future_sight(vec![fixture_source("testdata/lint_findings.nix")?]).or_fail()?;