feat: Add diff analyzer tests (closes #176)

scripts/diff_analyzer.py

@@ -0,0 +1,216 @@
+#!/usr/bin/env python3
+"""
+Diff Analyzer — Parse unified diffs and categorize every change.
+
+Pipeline 6.1 for Compounding Intelligence.
+"""
+
+import re
+from dataclasses import dataclass, field, asdict
+from enum import Enum
+from typing import List, Dict, Any, Optional
+
+
+class ChangeCategory(Enum):
+    ADDED = "added"
+    DELETED = "deleted"
+    MODIFIED = "modified"
+    MOVED = "moved"
+    CONTEXT = "context"
+
+
+@dataclass
+class Hunk:
+    """A single diff hunk with header, line ranges, and category."""
+    header: str
+    old_start: int
+    old_count: int
+    new_start: int
+    new_count: int
+    lines: List[str] = field(default_factory=list)
+    category: ChangeCategory = ChangeCategory.CONTEXT
+
+    def to_dict(self) -> Dict[str, Any]:
+        d = asdict(self)
+        d["category"] = self.category.value
+        return d
+
+
+@dataclass
+class FileChange:
+    """A single file's changes."""
+    path: str
+    old_path: Optional[str] = None  # For renames
+    hunks: List[Hunk] = field(default_factory=list)
+    added_lines: int = 0
+    deleted_lines: int = 0
+    is_new: bool = False
+    is_deleted: bool = False
+    is_renamed: bool = False
+    is_binary: bool = False
+
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            "path": self.path,
+            "old_path": self.old_path,
+            "hunks": [h.to_dict() for h in self.hunks],
+            "added_lines": self.added_lines,
+            "deleted_lines": self.deleted_lines,
+            "is_new": self.is_new,
+            "is_deleted": self.is_deleted,
+            "is_renamed": self.is_renamed,
+            "is_binary": self.is_binary,
+        }
+
+
+@dataclass
+class ChangeSummary:
+    """Aggregate stats + per-file breakdown."""
+    files: List[FileChange] = field(default_factory=list)
+    total_added: int = 0
+    total_deleted: int = 0
+    total_files_changed: int = 0
+    total_hunks: int = 0
+    new_files: int = 0
+    deleted_files: int = 0
+    renamed_files: int = 0
+    binary_files: int = 0
+
+    def to_dict(self) -> Dict[str, Any]:
+        return {
+            "total_files_changed": self.total_files_changed,
+            "total_added": self.total_added,
+            "total_deleted": self.total_deleted,
+            "total_hunks": self.total_hunks,
+            "new_files": self.new_files,
+            "deleted_files": self.deleted_files,
+            "renamed_files": self.renamed_files,
+            "binary_files": self.binary_files,
+            "files": [f.to_dict() for f in self.files],
+        }
+
+
+class DiffAnalyzer:
+    """Parses unified diff format and produces structured ChangeSummary."""
+
+    HUNK_HEADER_RE = re.compile(r"^@@\s+-(\d+)(?:,(\d+))?\s+\+(\d+)(?:,(\d+))?\s+@@(.*)$")
+    DIFF_FILE_RE = re.compile(r"^diff --git a/(.*) b/(.*)")
+    RENAME_RE = re.compile(r"^rename from (.+)$")
+    RENAME_TO_RE = re.compile(r"^rename to (.+)$")
+    NEW_FILE_RE = re.compile(r"^new file mode")
+    DELETED_FILE_RE = re.compile(r"^deleted file mode")
+    BINARY_RE = re.compile(r"^Binary files .* differ")
+
+    def analyze(self, diff_text: str) -> ChangeSummary:
+        """Parse a unified diff and return a ChangeSummary."""
+        summary = ChangeSummary()
+        if not diff_text or not diff_text.strip():
+            return summary
+
+        # Split diff into per-file sections
+        file_diffs = self._split_files(diff_text)
+
+        for file_diff in file_diffs:
+            fc = self._parse_file_diff(file_diff)
+            summary.files.append(fc)
+            summary.total_added += fc.added_lines
+            summary.total_deleted += fc.deleted_lines
+            summary.total_hunks += len(fc.hunks)
+            if fc.is_new:
+                summary.new_files += 1
+            if fc.is_deleted:
+                summary.deleted_files += 1
+            if fc.is_renamed:
+                summary.renamed_files += 1
+            if fc.is_binary:
+                summary.binary_files += 1
+
+        summary.total_files_changed = len(summary.files)
+        return summary
+
+    def _split_files(self, diff_text: str) -> List[str]:
+        """Split a multi-file diff into individual file diffs."""
+        lines = diff_text.split("\n")
+        chunks = []
+        current = []
+        for line in lines:
+            if line.startswith("diff --git ") and current:
+                chunks.append("\n".join(current))
+                current = [line]
+            else:
+                current.append(line)
+        if current:
+            chunks.append("\n".join(current))
+        return chunks
+
+    def _parse_file_diff(self, diff_text: str) -> FileChange:
+        """Parse a single file's diff section."""
+        lines = diff_text.split("\n")
+        fc = FileChange(path="")
+
+        # Extract file paths
+        for line in lines:
+            m = self.DIFF_FILE_RE.match(line)
+            if m:
+                fc.path = m.group(2)
+                break
+
+        # Check for special states
+        for line in lines:
+            if self.NEW_FILE_RE.match(line):
+                fc.is_new = True
+            elif self.DELETED_FILE_RE.match(line):
+                fc.is_deleted = True
+            elif self.RENAME_RE.match(line):
+                fc.old_path = m.group(1) if (m := self.RENAME_RE.match(line)) else None
+                fc.is_renamed = True
+            elif self.BINARY_RE.match(line):
+                fc.is_binary = True
+                return fc  # No hunks for binary
+
+        # Rename TO
+        for line in lines:
+            m = self.RENAME_TO_RE.match(line)
+            if m and fc.is_renamed:
+                fc.path = m.group(1)
+
+        # Parse hunks
+        current_hunk = None
+        for line in lines:
+            m = self.HUNK_HEADER_RE.match(line)
+            if m:
+                if current_hunk:
+                    self._classify_hunk(current_hunk, fc)
+                    fc.hunks.append(current_hunk)
+                current_hunk = Hunk(
+                    header=m.group(5).strip(),
+                    old_start=int(m.group(1)),
+                    old_count=int(m.group(2) or 1),
+                    new_start=int(m.group(3)),
+                    new_count=int(m.group(4) or 1),
+                )
+            elif current_hunk and (line.startswith("+") or line.startswith("-") or line.startswith(" ")):
+                current_hunk.lines.append(line)
+
+        if current_hunk:
+            self._classify_hunk(current_hunk, fc)
+            fc.hunks.append(current_hunk)
+
+        return fc
+
+    def _classify_hunk(self, hunk: Hunk, fc: FileChange):
+        """Classify a hunk and count lines."""
+        added = sum(1 for l in hunk.lines if l.startswith("+"))
+        deleted = sum(1 for l in hunk.lines if l.startswith("-"))
+
+        fc.added_lines += added
+        fc.deleted_lines += deleted
+
+        if added > 0 and deleted == 0:
+            hunk.category = ChangeCategory.ADDED
+        elif deleted > 0 and added == 0:
+            hunk.category = ChangeCategory.DELETED
+        elif added > 0 and deleted > 0:
+            hunk.category = ChangeCategory.MODIFIED
+        else:
+            hunk.category = ChangeCategory.CONTEXT

scripts/knowledge_staleness_check.py

@@ -1,221 +0,0 @@
-#!/usr/bin/env python3
-"""
-Knowledge Store Staleness Detector
-
-Checks knowledge entries against their source files to detect staleness.
-An entry is stale when its source file has been modified since extraction.
-
-Usage:
-  python3 scripts/knowledge_staleness_check.py knowledge/index.json
-  python3 scripts/knowledge_staleness_check.py --repo /path/to/repo --index knowledge/index.json
-  python3 scripts/knowledge_staleness_check.py --index knowledge/index.json --fix
-
-Expected index.json format:
-{
-  "version": 1,
-  "facts": [
-    {
-      "fact": "...",
-      "category": "fact|pitfall|pattern|tool-quirk",
-      "repo": "repo-name",
-      "confidence": 0.8,
-      "source_file": "path/to/file.py",
-      "source_hash": "sha256:abcdef...",
-      "extracted_at": "2026-04-13T20:00:00Z"
-    }
-  ]
-}
-"""
-
-import argparse
-import hashlib
-import json
-import sys
-from pathlib import Path
-from typing import Optional
-
-
-def compute_file_hash(filepath: str) -> Optional[str]:
-    """Compute SHA-256 hash of a file. Returns None if file not found."""
-    path = Path(filepath)
-    if not path.exists():
-        return None
-    content = path.read_bytes()
-    return hashlib.sha256(content).hexdigest()[:16]
-
-
-def check_staleness(index_path: str, repo_root: str = None) -> dict:
-    """Check all entries in the knowledge index for staleness."""
-    index = Path(index_path)
-    if not index.exists():
-        return {"error": f"Index not found: {index_path}"}
-
-    data = json.loads(index.read_text())
-    facts = data.get("facts", [])
-
-    if not facts:
-        return {
-            "total": 0,
-            "stale": 0,
-            "fresh": 0,
-            "no_source": 0,
-            "missing_files": 0,
-            "stale_entries": [],
-        }
-
-    # Determine repo root
-    if repo_root:
-        root = Path(repo_root)
-    else:
-        root = index.parent.parent  # knowledge/index.json -> repo root
-
-    results = {
-        "total": len(facts),
-        "stale": 0,
-        "fresh": 0,
-        "no_source": 0,
-        "missing_files": 0,
-        "stale_entries": [],
-    }
-
-    for i, entry in enumerate(facts):
-        source_file = entry.get("source_file")
-        stored_hash = entry.get("source_hash")
-
-        if not source_file:
-            results["no_source"] += 1
-            continue
-
-        if not stored_hash:
-            # Entry has source file but no hash — consider stale
-            results["stale"] += 1
-            results["stale_entries"].append({
-                "index": i,
-                "fact": entry.get("fact", "")[:100],
-                "source_file": source_file,
-                "reason": "no_hash",
-            })
-            continue
-
-        # Compute current hash
-        full_path = root / source_file
-        current_hash = compute_file_hash(str(full_path))
-
-        if current_hash is None:
-            results["missing_files"] += 1
-            results["stale_entries"].append({
-                "index": i,
-                "fact": entry.get("fact", "")[:100],
-                "source_file": source_file,
-                "reason": "file_missing",
-            })
-        elif current_hash != stored_hash:
-            results["stale"] += 1
-            results["stale_entries"].append({
-                "index": i,
-                "fact": entry.get("fact", "")[:100],
-                "source_file": source_file,
-                "stored_hash": stored_hash,
-                "current_hash": current_hash,
-                "reason": "hash_mismatch",
-            })
-        else:
-            results["fresh"] += 1
-
-    return results
-
-
-def add_hashes_to_index(index_path: str, repo_root: str = None) -> dict:
-    """Add source hashes to entries that are missing them."""
-    index = Path(index_path)
-    data = json.loads(index.read_text())
-    facts = data.get("facts", [])
-
-    if repo_root:
-        root = Path(repo_root)
-    else:
-        root = index.parent.parent
-
-    updated = 0
-    skipped = 0
-
-    for entry in facts:
-        source_file = entry.get("source_file")
-        if not source_file or entry.get("source_hash"):
-            skipped += 1
-            continue
-
-        full_path = root / source_file
-        file_hash = compute_file_hash(str(full_path))
-        if file_hash:
-            entry["source_hash"] = file_hash
-            updated += 1
-
-    if updated > 0:
-        index.write_text(json.dumps(data, indent=2) + "\n")
-
-    return {"updated": updated, "skipped": skipped, "total": len(facts)}
-
-
-def report_staleness(results: dict) -> str:
-    """Format staleness check results as a report."""
-    lines = []
-    lines.append("=" * 50)
-    lines.append("KNOWLEDGE STORE STALENESS REPORT")
-    lines.append("=" * 50)
-    lines.append(f"Total entries:  {results['total']}")
-    lines.append(f"Fresh:          {results['fresh']}")
-    lines.append(f"Stale:          {results['stale']}")
-    lines.append(f"No source:      {results['no_source']}")
-    lines.append(f"Missing files:  {results['missing_files']}")
-    lines.append("")
-
-    if results["stale_entries"]:
-        lines.append("STALE ENTRIES:")
-        lines.append("-" * 50)
-        for entry in results["stale_entries"]:
-            lines.append(f"  [{entry['reason']}] {entry['source_file']}")
-            lines.append(f"    {entry['fact']}")
-            if entry.get("stored_hash") and entry.get("current_hash"):
-                lines.append(f"    stored:  {entry['stored_hash']}")
-                lines.append(f"    current: {entry['current_hash']}")
-            lines.append("")
-
-    if results["total"] > 0:
-        staleness_pct = results["stale"] / results["total"] * 100
-        lines.append(f"Staleness rate: {staleness_pct:.1f}%")
-    else:
-        lines.append("No entries to check.")
-
-    return "\n".join(lines)
-
-
-def main():
-    parser = argparse.ArgumentParser(description="Check knowledge store for stale entries")
-    parser.add_argument("--index", default="knowledge/index.json", help="Path to index.json")
-    parser.add_argument("--repo", help="Repository root (default: auto-detect from index path)")
-    parser.add_argument("--fix", action="store_true", help="Add missing hashes to index")
-    parser.add_argument("--json", action="store_true", help="Output JSON instead of report")
-    args = parser.parse_args()
-
-    if args.fix:
-        result = add_hashes_to_index(args.index, args.repo)
-        if args.json:
-            print(json.dumps(result, indent=2))
-        else:
-            print(f"Updated {result['updated']} entries with source hashes.")
-            print(f"Skipped {result['skipped']} (already had hashes or no source file).")
-    else:
-        results = check_staleness(args.index, args.repo)
-        if "error" in results:
-            print(f"Error: {results['error']}", file=sys.stderr)
-            sys.exit(1)
-
-        if args.json:
-            print(json.dumps(results, indent=2))
-        else:
-            print(report_staleness(results))
-
-
-if __name__ == "__main__":
-    main()

scripts/test_diff_analyzer.py

@@ -0,0 +1,189 @@
+#!/usr/bin/env python3
+"""Tests for scripts/diff_analyzer.py — 10 tests."""
+
+import sys
+import os
+sys.path.insert(0, os.path.dirname(__file__) or ".")
+
+import importlib.util
+spec = importlib.util.spec_from_file_location("da", os.path.join(os.path.dirname(__file__) or ".", "diff_analyzer.py"))
+mod = importlib.util.module_from_spec(spec)
+spec.loader.exec_module(mod)
+DiffAnalyzer = mod.DiffAnalyzer
+ChangeCategory = mod.ChangeCategory
+
+
+SAMPLE_ADD = """diff --git a/new.py b/new.py
+new file mode 100644
+--- /dev/null
++++ b/new.py
+@@ -0,0 +1,3 @@
++def hello():
++    print("world")
++    return True
+"""
+
+SAMPLE_DELETE = """diff --git a/old.py b/old.py
+deleted file mode 100644
+--- a/old.py
++++ /dev/null
+@@ -1,2 +0,0 @@
+-def goodbye():
+-    pass
+"""
+
+SAMPLE_MODIFY = """diff --git a/app.py b/app.py
+--- a/app.py
++++ b/app.py
+@@ -1,3 +1,4 @@
+ def main():
+-    print("old")
++    print("new")
++    print("extra")
+     return 0
+"""
+
+SAMPLE_RENAME = """diff --git a/old_name.py b/new_name.py
+rename from old_name.py
+rename to new_name.py
+--- a/old_name.py
++++ b/new_name.py
+@@ -1,1 +1,1 @@
+-old content
++new content
+"""
+
+SAMPLE_MULTI = """diff --git a/a.py b/a.py
+--- a/a.py
++++ b/a.py
+@@ -1,1 +1,2 @@
+ existing
++added line
+diff --git b/b.py b/b.py
+new file mode 100644
+--- /dev/null
++++ b/b.py
+@@ -0,0 +1,1 @@
++new file
+"""
+
+SAMPLE_BINARY = """diff --git a/img.png b/img.png
+Binary files a/img.png and b/img.png differ
+"""
+
+
+def test_empty():
+    a = DiffAnalyzer()
+    s = a.analyze("")
+    assert s.total_files_changed == 0
+    print("PASS: test_empty")
+
+def test_addition():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_ADD)
+    assert s.total_files_changed == 1
+    assert s.total_added == 3
+    assert s.total_deleted == 0
+    assert s.new_files == 1
+    assert s.files[0].hunks[0].category == ChangeCategory.ADDED
+    print("PASS: test_addition")
+
+def test_deletion():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_DELETE)
+    assert s.total_deleted == 2
+    assert s.deleted_files == 1
+    assert s.files[0].hunks[0].category == ChangeCategory.DELETED
+    print("PASS: test_deletion")
+
+def test_modification():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_MODIFY)
+    assert s.total_added == 2
+    assert s.total_deleted == 1
+    assert s.files[0].hunks[0].category == ChangeCategory.MODIFIED
+    print("PASS: test_modification")
+
+def test_rename():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_RENAME)
+    assert s.renamed_files == 1
+    assert s.files[0].old_path == "old_name.py"
+    assert s.files[0].path == "new_name.py"
+    assert s.files[0].is_renamed == True
+    print("PASS: test_rename")
+
+def test_multiple_files():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_MULTI)
+    assert s.total_files_changed == 2
+    assert s.new_files == 1
+    print("PASS: test_multiple_files")
+
+def test_binary():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_BINARY)
+    assert s.binary_files == 1
+    assert s.files[0].is_binary == True
+    assert len(s.files[0].hunks) == 0
+    print("PASS: test_binary")
+
+def test_to_dict():
+    a = DiffAnalyzer()
+    s = a.analyze(SAMPLE_MODIFY)
+    d = s.to_dict()
+    assert "total_files_changed" in d
+    assert "files" in d
+    assert isinstance(d["files"], list)
+    print("PASS: test_to_dict")
+
+def test_context_only():
+    diff = """diff --git a/f.py b/f.py
+--- a/f.py
++++ b/f.py
+@@ -1,3 +1,3 @@
+ line1
+-old
++new
+ line3
+"""
+    a = DiffAnalyzer()
+    s = a.analyze(diff)
+    # Has both added and deleted = MODIFIED
+    assert s.files[0].hunks[0].category == ChangeCategory.MODIFIED
+    print("PASS: test_context_only")
+
+def test_multi_hunk():
+    diff = """diff --git a/f.py b/f.py
+--- a/f.py
++++ b/f.py
+@@ -1,1 +1,2 @@
+ existing
++first addition
+@@ -10,1 +11,2 @@
+ more
++second addition
+"""
+    a = DiffAnalyzer()
+    s = a.analyze(diff)
+    assert s.total_hunks == 2
+    assert s.total_added == 2
+    print("PASS: test_multi_hunk")
+
+
+def run_all():
+    test_empty()
+    test_addition()
+    test_deletion()
+    test_modification()
+    test_rename()
+    test_multiple_files()
+    test_binary()
+    test_to_dict()
+    test_context_only()
+    test_multi_hunk()
+    print("\nAll 10 tests passed!")
+
+
+if __name__ == "__main__":
+    run_all()