test: tighten brew helper coverage

src/infra/brew.test.ts

@@ -88,6 +88,35 @@ describe("brew helpers", () => {
     });
   });
 
+  it("ignores blank HOMEBREW_BREW_FILE and HOMEBREW_PREFIX values", async () => {
+    await withBrewRoot(async (tmp) => {
+      const homebrewBin = path.join(tmp, ".linuxbrew", "bin");
+      const brewPath = path.join(homebrewBin, "brew");
+      await writeExecutable(brewPath);
+
+      const env: NodeJS.ProcessEnv = {
+        HOMEBREW_BREW_FILE: "   ",
+        HOMEBREW_PREFIX: "\t",
+      };
+
+      expect(resolveBrewExecutable({ homeDir: tmp, env })).toBe(brewPath);
+
+      const dirs = resolveBrewPathDirs({ homeDir: tmp, env });
+      expect(dirs).not.toContain(path.join("", "bin"));
+      expect(dirs).not.toContain(path.join("", "sbin"));
+    });
+  });
+
+  it("always includes the standard macOS brew dirs after linuxbrew candidates", () => {
+    const env: NodeJS.ProcessEnv = {
+      HOMEBREW_BREW_FILE: "   ",
+      HOMEBREW_PREFIX: "   ",
+    };
+    const dirs = resolveBrewPathDirs({ homeDir: "/home/test", env });
+
+    expect(dirs.slice(-2)).toEqual(["/opt/homebrew/bin", "/usr/local/bin"]);
+  });
+
   it("includes Linuxbrew bin/sbin in path candidates", () => {
     const env: NodeJS.ProcessEnv = { HOMEBREW_PREFIX: "/custom/prefix" };
     const dirs = resolveBrewPathDirs({ homeDir: "/home/test", env });