sqlite-utils memory command for directly querying CSV/JSON data

* Turn SQL errors into click errors
* Initial CSV-only prototype of sqlite-utils memory, refs #272
* Implement --save plus tests for --save and --dump, refs #272
* Re-arranged CLI query documentation, refs #272
* Re-organized CLI query docs, refs #272
* Docs for --save and --dump plus made SQL optional for those, refs #273
* Replaced one last :memory: example
* Documented --attach option for memory command, refs #272
* Improved arrangement of CLI query documentation

tests/test_cli_memory.py

@@ -0,0 +1,72 @@
+from sqlite_utils import cli, Database
+from click.testing import CliRunner
+import pytest
+
+
+def test_memory_basic():
+    result = CliRunner().invoke(cli.cli, ["memory", "select 1 + 1"])
+    assert result.exit_code == 0
+    assert result.output.strip() == '[{"1 + 1": 2}]'
+
+
+@pytest.mark.parametrize("sql_from", ("test", "t", "t1"))
+@pytest.mark.parametrize("use_stdin", (True, False))
+def test_memory_csv(tmpdir, sql_from, use_stdin):
+    content = "id,name\n1,Cleo\n2,Bants"
+    input = None
+    if use_stdin:
+        input = content
+        csv_path = "-"
+        if sql_from == "test":
+            sql_from = "stdin"
+    else:
+        csv_path = str(tmpdir / "test.csv")
+        open(csv_path, "w").write(content)
+    result = CliRunner().invoke(
+        cli.cli,
+        ["memory", csv_path, "select * from {}".format(sql_from), "--nl"],
+        input=input,
+    )
+    assert result.exit_code == 0
+    assert (
+        result.output.strip()
+        == '{"id": "1", "name": "Cleo"}\n{"id": "2", "name": "Bants"}'
+    )
+
+
+@pytest.mark.parametrize("extra_args", ([], ["select 1"]))
+def test_memory_dump(extra_args):
+    result = CliRunner().invoke(
+        cli.cli,
+        ["memory", "-"] + extra_args + ["--dump"],
+        input="id,name\n1,Cleo\n2,Bants",
+    )
+    assert result.exit_code == 0
+    assert result.output.strip() == (
+        "BEGIN TRANSACTION;\n"
+        "CREATE TABLE [stdin] (\n"
+        "   [id] TEXT,\n"
+        "   [name] TEXT\n"
+        ");\n"
+        "INSERT INTO \"stdin\" VALUES('1','Cleo');\n"
+        "INSERT INTO \"stdin\" VALUES('2','Bants');\n"
+        "CREATE VIEW t1 AS select * from [stdin];\n"
+        "CREATE VIEW t AS select * from [stdin];\n"
+        "COMMIT;"
+    )
+
+
+@pytest.mark.parametrize("extra_args", ([], ["select 1"]))
+def test_memory_save(tmpdir, extra_args):
+    save_to = str(tmpdir / "save.db")
+    result = CliRunner().invoke(
+        cli.cli,
+        ["memory", "-"] + extra_args + ["--save", save_to],
+        input="id,name\n1,Cleo\n2,Bants",
+    )
+    assert result.exit_code == 0
+    db = Database(save_to)
+    assert list(db["stdin"].rows) == [
+        {"id": "1", "name": "Cleo"},
+        {"id": "2", "name": "Bants"},
+    ]