Validate instance version before SQL validation

spectacles/client.py

@@ -81,6 +81,64 @@ def authenticate(
 
         logger.info(f"Connected using Looker API {api_version}")
 
+    def get_looker_release_version(self) -> str:
+        """Gets the version number of connected Looker instance.
+
+        Returns:
+            str: Looker instance release version number (e.g. 6.22.12)
+
+        """
+        logger.debug("Checking Looker instance release version")
+
+        url = utils.compose_url(self.api_url, path=["versions"])
+
+        response = self.session.get(url=url)
+        try:
+            response.raise_for_status()
+        except requests.exceptions.HTTPError as error:
+            details = utils.details_from_http_error(response)
+            raise ApiConnectionError(
+                "Failed to get Looker instance release version\n"
+                f"Looker API error encountered: {error}\n"
+                + "Message received from Looker's API: "
+                f'"{details}"'
+            )
+
+        return response.json()["looker_release_version"]
+
+    def validate_looker_release_version(self, required_version: str) -> bool:
+        """Checks that the current Looker version meets a specified minimum.
+
+        Args:
+            required_version: Minimum instance version number (e.g. 6.22.12)
+
+        Returns:
+            bool: True if the current Looker version >= the required version
+
+        """
+        current_version = self.get_looker_release_version()
+        logger.info(f"Looker instance version is {current_version}")
+
+        def expand_version(version: str):
+            return [int(number) for number in version.split(".")]
+
+        current = expand_version(current_version)
+        required = expand_version(required_version)
+
+        # If version is provided in format 6.20 or 7, extend with .0(s)
+        # e.g. 6.20 would become 6.20.0, 7 would become 7.0.0
+        if len(current) < 3:
+            current.extend([0] * (3 - len(current)))
+
+        for current_num, required_num in zip(current, required):
+            if current_num < required_num:
+                return False
+            elif current_num > required_num:
+                return True
+
+        # Loop exits successfully if current version == required version
+        return True
+
     def update_session(self, project: str, branch: str) -> None:
         """Switches to a development mode session and checks out the desired branch.
 

spectacles/validators.py

@@ -43,9 +43,18 @@ class SqlValidator(Validator):
     """
 
     timeout = aiohttp.ClientTimeout(total=300)
+    MIN_LOOKER_VERSION = "6.22.12"
 
     def __init__(self, client: LookerClient, project: str):
         super().__init__(client)
+        meets_required_version = self.client.validate_looker_release_version(
+            required_version=self.MIN_LOOKER_VERSION
+        )
+        if not meets_required_version:
+            raise SpectaclesException(
+                "SQL validation requires version "
+                f"{self.MIN_LOOKER_VERSION} of Looker or higher."
+            )
         self.project = Project(project, models=[])
         self.query_tasks: dict = {}
 

tests/test_sql_validator.py

@@ -21,7 +21,16 @@ def load(filename):
 @pytest.fixture
 def client(monkeypatch):
     mock_authenticate = Mock(spec=LookerClient.authenticate)
+    mock_validate_looker_release_version = Mock(
+        spec=LookerClient.validate_looker_release_version
+    )
+    mock_validate_looker_release_version.return_value = True
     monkeypatch.setattr(LookerClient, "authenticate", mock_authenticate)
+    monkeypatch.setattr(
+        LookerClient,
+        "validate_looker_release_version",
+        mock_validate_looker_release_version,
+    )
     return LookerClient(TEST_BASE_URL, TEST_CLIENT_ID, TEST_CLIENT_SECRET)