diff --git a/packages/squiggle-lang/__tests__/GenericDist/GenericDistSparkline_Test.res b/packages/squiggle-lang/__tests__/GenericDist/GenericDistSparkline_Test.res
deleted file mode 100644
index 5aa72004..00000000
--- a/packages/squiggle-lang/__tests__/GenericDist/GenericDistSparkline_Test.res
+++ /dev/null
@@ -1,24 +0,0 @@
-open Jest
-open Expect
-
-let {normalDist, uniformDist, betaDist, lognormalDist, cauchyDist, triangularDist, exponentialDist} = module(GenericDist_Fixtures)
-
-let runTest = (name: string, dist : GenericDist_Types.genericDist, expected: string) => {
-  test(name, () => {
-    let result = GenericDist.toSparkline(dist, ~sampleCount=100, ~buckets=20, ())
-    switch result {
-    | Ok(sparkline) => expect(sparkline)->toEqual(expected)
-    | Error(err) => expect("Error")->toEqual(expected)
-  }
-  })
-}
-
-describe("sparkline of generic distribution", () => {
-  runTest("normal", normalDist, `▁▁▁▁▁▂▄▆▇██▇▆▄▂▁▁▁▁▁`)
-  runTest("uniform", uniformDist, `████████████████████`)
-  runTest("beta", betaDist, `▁▄▇████▇▆▅▄▃▃▂▁▁▁▁▁▁`)
-  runTest("lognormal", lognormalDist, `▁█▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁`)
-  runTest("cauchy", cauchyDist, `▁▁▁▁▁▁▁▁▁██▁▁▁▁▁▁▁▁▁`)
-  runTest("triangular", triangularDist, `▁▁▂▃▄▅▆▇████▇▆▅▄▃▂▁▁`)
-  runTest("exponential", exponentialDist, `█▅▄▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁`)
-})
diff --git a/packages/squiggle-lang/__tests__/GenericDist/GenericOperation__Test.res b/packages/squiggle-lang/__tests__/GenericDist/GenericOperation__Test.res
index c936e0bd..be01c87f 100644
--- a/packages/squiggle-lang/__tests__/GenericDist/GenericOperation__Test.res
+++ b/packages/squiggle-lang/__tests__/GenericDist/GenericOperation__Test.res
@@ -6,8 +6,18 @@ let env: DistributionOperation.env = {
   xyPointLength: 100,
 }
 
-
-let {normalDist5, normalDist10, normalDist20, uniformDist} = module(GenericDist_Fixtures)
+let {
+  normalDist5,
+  normalDist10,
+  normalDist20,
+  normalDist,
+  uniformDist,
+  betaDist,
+  lognormalDist,
+  cauchyDist,
+  triangularDist,
+  exponentialDist,
+} = module(GenericDist_Fixtures)
 let {toFloat, toDist, toString, toError} = module(DistributionOperation.Output)
 let {run} = module(DistributionOperation)
 let {fmap} = module(DistributionOperation.Output)
@@ -42,6 +52,57 @@ describe("mixture", () => {
   })
 })
 
+describe("sparkline", () => {
+  let runTest = (
+    name: string,
+    dist: GenericDist_Types.genericDist,
+    expected: DistributionOperation.outputType,
+  ) => {
+    test(name, () => {
+      let result = DistributionOperation.run(~env, FromDist(ToSparkline(20), dist))
+      expect(result)->toEqual(expected)
+    })
+  }
+
+  runTest(
+    "normal",
+    normalDist,
+    String(`▁▁▁▁▁▂▄▆▇██▇▆▄▂▁▁▁▁▁`),
+  )
+
+  runTest(
+    "uniform",
+    uniformDist,
+    String(`████████████████████`),
+  )
+
+  runTest("beta", betaDist, String(`▁▄▇████▇▆▅▄▃▃▂▁▁▁▁▁▁`))
+
+  runTest(
+    "lognormal",
+    lognormalDist,
+    String(`▁█▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁`),
+  )
+
+  runTest(
+    "cauchy",
+    cauchyDist,
+    String(`▁▁▁▁▁▁▁▁▁██▁▁▁▁▁▁▁▁▁`),
+  )
+
+  runTest(
+    "triangular",
+    triangularDist,
+    String(`▁▁▂▃▄▅▆▇████▇▆▅▄▃▂▁▁`),
+  )
+
+  runTest(
+    "exponential",
+    exponentialDist,
+    String(`█▅▄▂▂▁▁▁▁▁▁▁▁▁▁▁▁▁▁▁`),
+  )
+})
+
 describe("toPointSet", () => {
   test("on symbolic normal distribution", () => {
     let result =