sh: and python: YAML commands, refs #155

docs/multi.md

@@ -122,6 +122,35 @@ You can now take screenshots of `http://localhost:8000/` and any other URLs that
 ```
 The server process will be automatically terminated when the `shot-scraper multi` command completes.
 
+## Running custom code between steps
+
+If you are taking screenshots of a single application, you may find it useful to run additional steps between shots that modify that application in some way.
+
+You can do that using the `sh:` or `python:` keys. These can specify shell commands or Python code to run before taking the screenshot:
+
+```yaml
+- sh: echo "Hello from shell" > index.html
+  output: from-shell.png
+  url: http://localhost:8000/
+```
+You can also specify a list of shell arguments like this:
+```yaml
+- sh:
+  - curl
+  - -o
+  - index.html
+  - https://www.example.com/
+  output: example.png
+  url: http://localhost:8000/
+```
+If you specify these steps without a `url:` key they will still execute as individual task executions, without also taking a screenshot:
+```yaml
+- sh: echo "hello world" > index.html
+- python: |
+    content = open("index.html").read()
+    open("index.html", "w").write(content.upper())
+```
+
 ## `shot-scraper multi --help`
 
 Full `--help` for this command:

shot_scraper/cli.py

@@ -540,8 +540,20 @@ def multi(
                     and pathlib.Path(shot["output"]).exists()
                 ):
                     continue
-                if outputs and shot.get("output") not in outputs:
+                if outputs and shot.get("output") and shot.get("output") not in outputs:
                     continue
+                # Run "sh" key
+                if shot.get("sh"):
+                    sh = shot["sh"]
+                    if isinstance(sh, str):
+                        subprocess.run(shot["sh"], shell=True)
+                    elif isinstance(sh, list):
+                        subprocess.run(sh)
+                    else:
+                        raise click.ClickException("- sh: must be a string or list")
+                # And "python" key
+                if shot.get("python"):
+                    subprocess.run([sys.executable, "-c", shot["python"]])
                 if "server" in shot:
                     # Start that subprocess and remember the pid
                     server_processes.append(
@@ -1098,7 +1110,7 @@ def take_shot(
 
     url = url_or_file_path(url, file_exists=_check_and_absolutize)
 
-    output = shot.get("output", "").strip()
+    output = (shot.get("output") or "").strip()
     if not output and not return_bytes:
         output = filename_for_url(url, ext="png", file_exists=os.path.exists)
     quality = shot.get("quality")

tests/test_shot_scraper.py

@@ -1,4 +1,5 @@
 from click.testing import CliRunner
+import pathlib
 import pytest
 import textwrap
 from shot_scraper.cli import cli
@@ -15,17 +16,39 @@ def test_version():
 SERVER_YAML = """
 - server: python -m http.server 9023
 - url: http://localhost:9023/
-  output: {}
+  output: output.png
 """.strip()
 
+COMMANDS_YAML = """
+- sh: echo "hello world" > index.html
+- sh:
+  - touch
+  - touched.html
+- python: |
+    content = open("index.html").read()
+    open("index.html", "w").write(content.upper())
+"""
+
 
-def test_multi_server(tmpdir):
-    yaml_file = tmpdir / "server.yaml"
-    yaml_file.write(SERVER_YAML.format(tmpdir / "output.png"))
+def test_multi_server():
     runner = CliRunner()
-    result = runner.invoke(cli, ["multi", str(yaml_file)])
-    assert result.exit_code == 0, result.output
-    assert (tmpdir / "output.png").exists()
+    with runner.isolated_filesystem():
+        open("server.yaml", "w").write(SERVER_YAML)
+        result = runner.invoke(cli, ["multi", "server.yaml"])
+        assert result.exit_code == 0, result.output
+        assert pathlib.Path("output.png").exists()
+
+
+def test_multi_commands():
+    runner = CliRunner()
+    with runner.isolated_filesystem():
+        yaml_file = "commands.yaml"
+        open(yaml_file, "w").write(COMMANDS_YAML)
+        result = runner.invoke(cli, ["multi", yaml_file], catch_exceptions=False)
+        assert result.exit_code == 0, result.output
+        assert pathlib.Path("touched.html").exists()
+        assert pathlib.Path("index.html").exists()
+        assert open("index.html").read().strip() == "HELLO WORLD"
 
 
 @pytest.mark.parametrize("input", ("key: value", "This is a string", "3.55"))