Add example env file generator

CHANGELOG.md

@@ -385,4 +385,4 @@ project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 [0.12.0]: https://github.com/theskumar/python-dotenv/compare/v0.11.0...v0.12.0
 [0.11.0]: https://github.com/theskumar/python-dotenv/compare/v0.10.5...v0.11.0
 [0.10.5]: https://github.com/theskumar/python-dotenv/compare/v0.10.4...v0.10.5
-[0.10.4]: https://github.com/theskumar/python-dotenv/compare/v0.10.3...v0.10.4
+[0.10.4]: https://github.com/theskumar/python-dotenv/compare/v0.10.3...v0.10.4

src/dotenv/cli.py

@@ -121,7 +121,6 @@ def get(ctx: click.Context, key: Any) -> None:
     else:
         exit(1)
 
-
 @cli.command()
 @click.pass_context
 @click.argument('key', required=True)
@@ -165,6 +164,34 @@ def run(ctx: click.Context, override: bool, commandline: List[str]) -> None:
     exit(ret)
 
 
+@cli.command()
+@click.pass_context
+def generate_sample(ctx: click.Context) -> None:
+    '''Generates a .example.env file without values.'''
+    filedir = ctx.obj['FILE'].replace("\\", "/")
+    if not os.path.isfile(filedir):
+        raise click.BadParameter(
+            'Path "%s" does not exist.' % (filedir),
+            ctx=ctx
+        )
+    newEnvList = []
+    with open(filedir, 'r') as file:
+        for line in file:
+            line = line.strip()
+            if line[0] != "#":
+                line = line.replace(" ", "").replace("=", " = ").split("=", 1)[0] + "="
+            else:
+                line = "# " + line[1:].strip()  # inserts space between comment and '#'
+            newEnvList.append(line)  # slicing removes trailing newline
+        newEnvList[-1] += "\n"
+
+    while newEnvList[-1] == "\n":
+        newEnvList.pop(-1)
+
+    for line in newEnvList:
+        click.echo(line)
+
+
 def run_command(command: List[str], env: Dict[str, str]) -> int:
     """Run command in sub process.
 

tests/test_cli.py

@@ -238,3 +238,29 @@ def test_run_with_version(cli):
 
     assert result.exit_code == 0
     assert result.output.strip().endswith(__version__)
+
+
+def test_generate_sample_non_existent_file(cli):
+    result = cli.invoke(dotenv_cli, ['--file', 'nx_file', 'generate-sample'])
+
+    assert result.exit_code == 2
+    assert "does not exist" in result.output
+
+
+def test_generate_sample_cleanup_and_comment_preservation(cli, dotenv_file):
+    sample = "# a = b\n#c = d\n  # e=f\n  #g = h\ni=j"
+    with open(dotenv_file, "w") as f:
+        f.write(sample)
+    result = cli.invoke(dotenv_cli, ['--file', dotenv_file, 'generate-sample'])
+
+    assert result.exit_code == 0
+    assert result.output == "# a = b\n# c = d\n# e=f\n# g = h\ni =\n\n"
+
+
+def test_generate_sample_value_removal(cli, dotenv_file):
+    with open(dotenv_file, "w") as f:
+        f.write("a=b")
+    result = cli.invoke(dotenv_cli, ['--file', dotenv_file, 'generate-sample'])
+
+    assert result.exit_code == 0, result.output
+    assert 'b' not in result.output