bench: add test_plots

tests/benchmarks/cli/commands/test_plots.py

@@ -0,0 +1,68 @@
+from textwrap import dedent
+
+import pytest
+
+
+@pytest.fixture
+def repo_with_plots(tmp_dir, scm, dvc):
+    num_files = 20
+    CODE = dedent(
+        """
+    from random import random
+    import sys
+
+    num_files = {num_files}
+    linspace_size = 1000
+
+    def load_params():
+        import yaml
+        with open('params.yaml') as fd:
+                return yaml.safe_load(fd)
+
+    params = load_params()
+    p = params['p']
+
+    def calc_metric(index):
+        metric = [(i/linspace_size)**p + (random()-0.5)/index
+                  for i in range(1,linspace_size)]
+
+        result=[]
+        for elem in list(metric):
+            result.append({{f'val_{{index}}': elem}})
+        return result
+
+    import json
+    if __name__ == '__main__':
+        for i in range(1, num_files+1):
+            metric = calc_metric(i)
+            with open(f'metric_{{i}}.json', 'w') as fd:
+                json.dump(metric, fd)
+    """
+    ).format(num_files=num_files)
+
+    tmp_dir.gen("train.py", CODE)
+    tmp_dir.gen("params.yaml", "p: 1")
+    scm.add(["train.py", "params.yaml"])
+    scm.commit("initial")
+
+    dvc.run(
+        name="generate_plots",
+        deps=["train.py"],
+        plots=[f"metric_{i}.json" for i in range(1, num_files + 1)],
+        params=["p"],
+        cmd="python train.py",
+    )
+
+    scm.add(["dvc.lock", "dvc.yaml"])
+    scm.commit("initial run, p=1")
+
+    tmp_dir.gen("params.yaml", "p: 3")
+    dvc.reproduce()
+
+    yield
+
+
+def test_plots_diff(tmp_dir, bench_dvc, repo_with_plots):
+    bench_dvc("plots", "diff")
+
+    assert (tmp_dir / "dvc_plots" / "index.html").is_file()