2 files changed, 89 insertions, 0 deletions

diff --git a/src/app.test.ts b/src/app.test.ts
index 265465e..8519d91 100644
--- a/src/app.test.ts
+++ b/src/app.test.ts
@@ -155,6 +155,62 @@ describe("blob view", () => {
   });
 });
 
+describe("commit history", () => {
+  const repo = { owner: "actions", name: "deploy-pages" };
+  const oid = "b39c421b98f49d83ae50ec502c3ddfc3bf28f2c6";
+  const commitGroups = [
+    {
+      title: "Apr 18, 2023",
+      commits: [
+        { oid, shortMessage: "Remove deprecated input parameters", authors: [{ login: "jmg" }] },
+      ],
+    },
+  ];
+  const history = { repo, branch: "main", path: "src/index.js", commitGroups };
+
+  // A commits payload never says whether its path is a file or a directory, so
+  // every link goes to the tree and GitHub redirects a file's to its blob.
+  it("should browse a file's history at each of its commits", () => {
+    const html = eta.render("commits.eta", history);
+
+    assert.match(html, new RegExp(`href="/actions/deploy-pages/blob/${oid}/src/index.js">Browse`));
+  });
+
+  it("should browse a directory's history the same way", () => {
+    const html = eta.render("commits.eta", { ...history, path: "src" });
+
+    assert.match(html, new RegExp(`href="/actions/deploy-pages/blob/${oid}/src">Browse`));
+  });
+
+  it("should browse the whole repository when the history has no path", () => {
+    const html = eta.render("commits.eta", { ...history, path: "" });
+
+    assert.match(html, new RegExp(`href="/actions/deploy-pages/blob/${oid}">Browse`));
+  });
+
+  // Walking up from a history stays in the history, and its last crumb is the
+  // page you are already on, just as a blob or a tree ends on itself.
+  it("should walk up through the history of each parent directory", () => {
+    const html = eta.render("commits.eta", { ...history, path: "src/lib/index.js" });
+
+    assert.match(html, /href="\/actions\/deploy-pages\/commits\/main">\(top\)</);
+    assert.match(html, /href="\/actions\/deploy-pages\/commits\/main\/src">src</);
+    assert.match(html, /href="\/actions\/deploy-pages\/commits\/main\/src\/lib">lib<\/a>\/index\.js/);
+  });
+
+  it("should say so when a path has no history", () => {
+    const html = eta.render("commits.eta", { ...history, commitGroups: [] });
+
+    assert.match(html, /No commits found\./);
+  });
+
+  it("should link a blob to its own history", () => {
+    const html = eta.render("blob.eta", { ...history, textLines: ["x"] });
+
+    assert.match(html, /href="\/actions\/deploy-pages\/commits\/main\/src\/index.js">History/);
+  });
+});
+
 describe("embedded files", () => {
   function stubGitHub(t: TestContext, body: string, contentType: string, status = 200) {
     t.mock.method(
diff --git a/src/scraper.test.ts b/src/scraper.test.ts
index 2690f71..f6be2b6 100644
--- a/src/scraper.test.ts
+++ b/src/scraper.test.ts
@@ -195,6 +195,39 @@ describe("GitHub scraper", () => {
       assert.ok(data.commitGroups.length > 0);
     });
 
+    // GitHub serves a file's history from the same route as a directory's.
+    it("should fetch the history of a blob", async () => {
+      const data = await getGitHubCommits("actions", "deploy-pages", "main", "src/index.js");
+
+      assert.strictEqual(data.path, "src/index.js");
+
+      assert.ok(data.commitGroups.length > 0);
+      const commit = data.commitGroups[0].commits[0];
+      assert.strictEqual(commit.oid.length, 40);
+      assert.ok(commit.shortMessage.length > 0);
+    });
+
+    // What a history page's "Browse" link resolves to: the file as it stood at
+    // one of its commits. Nothing in a commits payload says whether the path is
+    // a file or a directory, so those links all point at the tree and rely on
+    // GitHub redirecting a file's to its blob.
+    it("should redirect a blob browsed at a commit to its blob view", async () => {
+      const oid = "b39c421b98f49d83ae50ec502c3ddfc3bf28f2c6";
+
+      await assert.rejects(getGitHubTree("actions", "deploy-pages", oid, "src/index.js"), (err) => {
+        assert(err instanceof RedirectError, "error should be a RedirectError");
+        assert.strictEqual(err.location, `/actions/deploy-pages/blob/${oid}/src/index.js`);
+        return true;
+      });
+
+      const data = await getGitHubBlob("actions", "deploy-pages", oid, "src/index.js");
+
+      assert.strictEqual(data.branch, oid);
+      assert.strictEqual(data.path, "src/index.js");
+      assert.strictEqual(data.size, "1.37 KB / 51 lines / 40 loc");
+      assert.strictEqual(data.textLines?.length, 51);
+    });
+
     it("should fetch releases", async () => {
       const data = await getGitHubReleases("actions", "deploy-pages");