implement custom output path flag and integration tests

main.cpp

@@ -25,6 +25,7 @@ struct Bucket {
 
 int main(int argc, char *argv[]) {
     bool quiet = false;
+    std::string output_path = "palette.json";
     std::string imagefile;
     for (int i = 1; i < argc; i++) {
         std::string arg = argv[i];
@@ -34,14 +35,20 @@ int main(int argc, char *argv[]) {
                 "Usage:\n"
                 "  " << argv[0] << " <image> [options]\n\n"
                 "Options:\n"
-                "  -h, --help      Show this help page\n"
+                "  -h, --help           Show this help page\n"
-                "  -q, --quiet     Suppress terminal output (JSON is still written)\n\n"
+                "  -q, --quiet          Suppress terminal output (JSON is still written)\n"
+                "  -o, --output <file>  Write JSON palette to <file> (default: palette.json)\n\n"
                 "Output:\n"
                 "  Prints dominant colors as HEX and terminal swatches\n"
-                "  Also writes palette.json\n";
+                "  Also writes palette.json (or the path given with -o)\n";
             return 0;
         } else if (arg == "--quiet" || arg == "-q") {
             quiet = true;
+        } else if ((arg == "--output" || arg == "-o") && i + 1 < argc) {
+            output_path = argv[++i];
+        } else if ((arg == "--output" || arg == "-o") && i + 1 >= argc) {
+            cout << "Option " << arg << " requires an argument.\n";
+            return 1;
         } else if (imagefile.empty()) {
             imagefile = arg;
         } else {
@@ -167,7 +174,12 @@ int main(int argc, char *argv[]) {
 
     int paletteSize = std::min(5, (int)buckets.size());
 
-    std::ofstream json("palette.json");
+    std::ofstream json(output_path);
+    if (!json) {
+        cout << "Cannot open output file: " << output_path << "\n";
+        stbi_image_free(data);
+        return 1;
+    }
 
     json << "{\n";
     json << "   \"image\": \"" << imagefile << "\",\n";

test_runner.py

@@ -126,6 +126,34 @@ def test_invalid_format(binary, workdir):
             "missing unknown-image-format message")
 
 
+def test_custom_output(binary, workdir):
+    img = os.path.join(workdir, "solid.png")
+    make_png(img, 40, 40, (100, 150, 200))
+    custom_json = os.path.join(workdir, "custom_palette.json")
+    rc, out = run(binary, img, "-o", custom_json, cwd=workdir)
+    assert_(rc == 0, "custom-output: expected exit 0, got %d" % rc)
+    assert_(os.path.exists(custom_json), "custom JSON file was not written at: %s" % custom_json)
+    # Default palette.json must NOT be written when -o is given with a different path.
+    default_json = os.path.join(workdir, "palette.json")
+    assert_(not os.path.exists(default_json), "default palette.json should not be written when -o is used")
+    with open(custom_json) as f:
+        data = json.load(f)
+    assert_(data["image"] == img, "custom palette.json image field mismatch")
+    palette = data["palette"]
+    assert_(isinstance(palette, list) and 1 <= len(palette) <= 5,
+            "palette must be a non-empty list of at most 5 entries")
+
+
+def test_custom_output_bad_path(binary, workdir):
+    img = os.path.join(workdir, "solid.png")
+    make_png(img, 40, 40, (100, 150, 200))
+    bad_path = os.path.join(workdir, "nonexistent_dir", "out.json")
+    rc, out = run(binary, img, "-o", bad_path, cwd=workdir)
+    assert_(rc != 0, "bad-output-path: expected non-zero exit, got 0")
+    assert_(b"Cannot open output file" in out,
+            "missing 'Cannot open output file' error message")
+
+
 def main():
     if len(sys.argv) < 2:
         print("usage: %s <path-to-ccolors-binary>" % sys.argv[0], file=sys.stderr)
@@ -141,6 +169,8 @@ def main():
         ("happy_path_jpeg", lambda d: test_happy_path_jpeg(binary, d)),
         ("file_not_found", lambda d: test_file_not_found(binary, d)),
         ("invalid_format", lambda d: test_invalid_format(binary, d)),
+        ("custom_output", lambda d: test_custom_output(binary, d)),
+        ("custom_output_bad_path", lambda d: test_custom_output_bad_path(binary, d)),
     ]
     failures = []
     for name, fn in tests: