Raise error in build step if custom component package is not installed (#7046)

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* add changeset

---------

Co-authored-by: gradio-pr-bot <gradio-pr-bot@users.noreply.github.com>

.changeset/huge-dogs-suffer.md

@@ -0,0 +1,5 @@
+---
+"gradio": patch
+---
+
+fix:Raise error in build step if custom component package is not installed

gradio/cli/commands/components/build.py

@@ -1,3 +1,4 @@
+import importlib
 import shutil
 import subprocess
 from pathlib import Path
@@ -34,6 +35,14 @@ def _build(
             f":package: Building package in [orange3]{str(name.name)}[/]", add_sleep=0.2
         )
         pyproject_toml = parse((path / "pyproject.toml").read_text())
+        package_name = pyproject_toml["project"]["name"]  # type: ignore
+        try:
+            importlib.import_module(package_name)  # type: ignore
+        except ModuleNotFoundError as e:
+            raise ValueError(
+                f"Your custom component package ({package_name}) is not installed! "
+                "Please install it with the gradio cc install command before buillding it."
+            ) from e
         if bump_version:
             pyproject_toml = parse((path / "pyproject.toml").read_text())
             version = semantic_version.Version(

test/test_gradio_component_cli.py

@@ -5,6 +5,7 @@ from pathlib import Path
 import pytest
 
 from gradio.cli.commands.components._create_utils import OVERRIDES
+from gradio.cli.commands.components.build import _build
 from gradio.cli.commands.components.create import _create
 from gradio.cli.commands.components.publish import _get_version_from_file
 from gradio.cli.commands.components.show import _show
@@ -146,6 +147,22 @@ def test_build(template, virtualenv):
         shutil.rmtree(str(dir_), ignore_errors=True)
 
 
+def test_build_fails_if_component_not_installed(tmp_path):
+    _create(
+        "MyComponent",
+        tmp_path,
+        template="SimpleTextbox",
+        overwrite=True,
+        install=False,
+        configure_metadata=False,
+    )
+    with pytest.raises(
+        ValueError,
+        match=r"Your custom component package \(gradio_mycomponent\) is not installed!",
+    ):
+        _build(tmp_path)
+
+
 def test_fallback_template_app(tmp_path):
     _create(
         "SimpleComponent2",