graphing: serve rrdtool graphs over http

test/GraphingSpec.hs

@@ -2,6 +2,8 @@
 
 module GraphingSpec (spec) where
 
+import Control.Exception (SomeException, finally, try)
+import qualified Data.ByteString as BS
 import HomeAssistant.Runtime.Graphing
   ( GraphSpec (..)
   , Range (..)
@@ -11,7 +13,12 @@ import HomeAssistant.Runtime.Graphing
   , parseNameParam
   , parseRange
   , rangeStart
+  , readProcessBytes
   )
+import qualified HomeAssistant.Runtime.Metrics as Metrics
+import System.Directory (findExecutable, getTemporaryDirectory, removeFile)
+import System.Exit (ExitCode (..))
+import System.Process (readProcessWithExitCode)
 import Test.Hspec
 
 traffic :: GraphSpec
@@ -82,4 +89,38 @@ spec = do
           , "CDEF:svc_min=svc,60,*"
           , "LINE2:trig_min#0066cc:triggers in/min"
           , "LINE2:svc_min#cc0000:services out/min"
-          ]
+          ]
+
+  describe "end-to-end (rrdtool-gated)" $ do
+    it "renders a PNG for the traffic graph" $ do
+      mRrdtool <- findExecutable "rrdtool"
+      case mRrdtool of
+        Nothing -> pendingWith "rrdtool not on PATH"
+        Just rrdtool -> do
+          tmp <- getTemporaryDirectory
+          let rrdPath = tmp ++ "/hass-controller-graph-test.rrd"
+              cleanup = try (removeFile rrdPath) :: IO (Either SomeException ())
+              schema =
+                [ ("hass_trigger_in", Metrics.Derive)
+                , ("hass_service_out", Metrics.Derive)
+                ]
+              pngMagic = BS.pack [0x89, 0x50, 0x4E, 0x47, 0x0D, 0x0A, 0x1A, 0x0A]
+          _ <- cleanup
+          ( do
+              (createCode, _, _) <-
+                readProcessWithExitCode rrdtool (Metrics.buildCreateArgs rrdPath 10 schema) ""
+              createCode `shouldBe` ExitSuccess
+              (updateCode, _, _) <-
+                readProcessWithExitCode
+                  rrdtool
+                  (Metrics.buildUpdateArgs
+                    rrdPath
+                    ["hass_trigger_in", "hass_service_out"]
+                    [Just 5, Just 3])
+                  ""
+              updateCode `shouldBe` ExitSuccess
+              (code, out, _) <- readProcessBytes rrdtool (buildGraphArgs rrdPath traffic OneHour)
+              code `shouldBe` ExitSuccess
+              out `shouldSatisfy` BS.isPrefixOf pngMagic
+            )
+            `finally` cleanup