gites: colorful git tree viewer

Tauri 2 + Vue app that draws the commit graph of the repository given on
the command line. Branches can be hidden one by one or by patterns,
runs of plain commits fold into a dotted line, and everything is
reachable from the keyboard.

src/lib/layout.test.ts

@@ -0,0 +1,47 @@
+import { describe, expect, it } from "vitest";
+import { layout } from "./layout";
+
+const row = (hash: string, ...parents: string[]) => ({
+  commit: { hash },
+  parents: parents.map((p) => ({ hash: p.replace("~", ""), dotted: p.startsWith("~") })),
+});
+
+describe("layout", () => {
+  it("puts a straight line in one column with one color", () => {
+    const r = layout([row("c", "b"), row("b", "a"), row("a")]);
+    expect(r.rows.map((x) => x.col)).toEqual([0, 0, 0]);
+    expect(new Set(r.rows.map((x) => x.color)).size).toBe(1);
+    expect(r.width).toBe(1);
+  });
+
+  it("opens a second column for a merged branch and joins it back", () => {
+    const r = layout([row("m", "a", "b"), row("b", "a"), row("a")]);
+    expect(r.rows.map((x) => x.col)).toEqual([0, 1, 0]);
+    expect(r.rows[1].color).not.toBe(r.rows[0].color);
+    expect(r.width).toBe(2);
+    // Below b, its line bends from column 1 back into column 0.
+    expect(r.rows[1].segments).toContainEqual(
+      expect.objectContaining({ x1: 1, y1: 0.5, x2: 0, y2: 1 }),
+    );
+  });
+
+  it("draws a line that passes a row as a straight segment", () => {
+    const r = layout([row("m", "a", "b"), row("b", "a"), row("a")]);
+    // At row b, column 0 is still waiting for a.
+    expect(r.rows[1].segments).toContainEqual(
+      expect.objectContaining({ x1: 0, y1: 0, x2: 0, y2: 1 }),
+    );
+  });
+
+  it("starts a new column for a second branch tip", () => {
+    const r = layout([row("x", "a"), row("y", "a"), row("a")]);
+    expect(r.rows.map((x) => x.col)).toEqual([0, 1, 0]);
+  });
+
+  it("carries dotted edges down to the parent", () => {
+    const r = layout([row("m", "a", "~b"), row("z", "q"), row("q"), row("b", "a"), row("a")]);
+    const dotted = r.rows.flatMap((x) => x.segments).filter((s) => s.dotted);
+    expect(dotted.length).toBeGreaterThan(0);
+    expect(r.rows[3].segments.some((s) => s.dotted && s.y2 === 0.5)).toBe(true);
+  });
+});