From 9559a410d3cbc3af63f2cbc0af3140d50007ce21 Mon Sep 17 00:00:00 2001
From: Stuart Axelbrooke <stuart@axelbrooke.com>
Date: Thu, 16 Oct 2025 19:33:18 -0700
Subject: [PATCH] impl log line parsing

---
 databuild/data_deps.rs | 35 ++++++++++++++++++++++++++++++++---
 1 file changed, 32 insertions(+), 3 deletions(-)

diff --git a/databuild/data_deps.rs b/databuild/data_deps.rs
index 4bc9b6e..03081aa 100644
--- a/databuild/data_deps.rs
+++ b/databuild/data_deps.rs
@@ -2,8 +2,7 @@ use crate::JobRunMissingDeps;
 
 pub struct LogLine(String);
 
-const DATABUILD_JSON: &str = "DATABUILD_JSON:";
-const DATABUILD_JSON_LEN: usize = DATABUILD_JSON.len();
+const DATABUILD_JSON: &str = "DATABUILD_MISSING_DEPS_JSON:";
 
 impl From<LogLine> for Option<JobRunMissingDeps> {
     fn from(value: LogLine) -> Self {
@@ -16,6 +15,36 @@ fn line_matches(line: &str) -> Option<&str> {
 }
 
 fn json_to_missing_deps(line: &str) -> Option<JobRunMissingDeps> {
-    todo!()
+    serde_json::from_str(line).ok()
 }
 
+#[cfg(test)]
+mod tests {
+    use super::*;
+
+    #[test]
+    fn test_parse_missing_deps_with_1_to_1_and_1_to_n() {
+        let log_line = LogLine(
+            r#"DATABUILD_MISSING_DEPS_JSON:{"missing_deps":[{"impacted":[{"ref":"output/p1"}],"missing":[{"ref":"input/p1"}]},{"impacted":[{"ref":"output/p2"},{"ref":"output/p3"}],"missing":[{"ref":"input/p2"}]}]}"#.to_string()
+        );
+
+        let result: Option<JobRunMissingDeps> = log_line.into();
+        assert!(result.is_some());
+
+        let missing_deps = result.unwrap();
+        assert_eq!(missing_deps.missing_deps.len(), 2);
+
+        // First entry: 1:1 (one missing input -> one impacted output)
+        assert_eq!(missing_deps.missing_deps[0].impacted.len(), 1);
+        assert_eq!(missing_deps.missing_deps[0].impacted[0].r#ref, "output/p1");
+        assert_eq!(missing_deps.missing_deps[0].missing.len(), 1);
+        assert_eq!(missing_deps.missing_deps[0].missing[0].r#ref, "input/p1");
+
+        // Second entry: 1:N (one missing input -> multiple impacted outputs)
+        assert_eq!(missing_deps.missing_deps[1].impacted.len(), 2);
+        assert_eq!(missing_deps.missing_deps[1].impacted[0].r#ref, "output/p2");
+        assert_eq!(missing_deps.missing_deps[1].impacted[1].r#ref, "output/p3");
+        assert_eq!(missing_deps.missing_deps[1].missing.len(), 1);
+        assert_eq!(missing_deps.missing_deps[1].missing[0].r#ref, "input/p2");
+    }
+}