Add basic partial test

packages/squiggle-lang/__tests__/TS/JS_test.ts

@@ -1,5 +1,5 @@
 import { Distribution, resultMap } from "../../src/js/index";
-import { testRun } from "./TestHelpers";
+import { testRun, testRunPartial } from "./TestHelpers";
 
 function Ok<b>(x: b) {
   return { tag: "Ok", value: x };
@@ -57,6 +57,17 @@ describe("Record", () => {
   });
 });
 
+describe("Partials", () => {
+  test("Can pass variables between partials and cells", () => {
+    let bindings = testRunPartial(`x = 5`);
+    let bindings2 = testRunPartial(`y = x + 2`, bindings);
+    expect(testRun(`y + 3`, bindings2)).toEqual({
+      tag: "number",
+      value: 10,
+    });
+  });
+});
+
 describe("Distribution", () => {
   //It's important that sampleCount is less than 9. If it's more, than that will create randomness
   //Also, note, the value should be created using makeSampleSetDist() later on.

packages/squiggle-lang/__tests__/TS/TestHelpers.ts

@@ -1,14 +1,16 @@
 import {
   run,
-  // Distribution,
+  runPartial,
+  bindings,
   squiggleExpression,
   errorValueToString,
-  // errorValue,
-  // result,
 } from "../../src/js/index";
 
-export function testRun(x: string): squiggleExpression {
-  let squiggleResult = run(x, {}, { sampleCount: 1000, xyPointLength: 100 });
+export function testRun(x: string, bindings = {}): squiggleExpression {
+  let squiggleResult = run(x, bindings, {
+    sampleCount: 1000,
+    xyPointLength: 100,
+  });
   // return squiggleResult.value
   if (squiggleResult.tag === "Ok") {
     return squiggleResult.value;
@@ -21,6 +23,22 @@ export function testRun(x: string): squiggleExpression {
   }
 }
 
+export function testRunPartial(x: string, bindings: bindings = {}): bindings {
+  let squiggleResult = runPartial(x, bindings, {
+    sampleCount: 1000,
+    xyPointLength: 100,
+  });
+  if (squiggleResult.tag === "Ok") {
+    return squiggleResult.value;
+  } else {
+    throw new Error(
+      `Expected squiggle expression to evaluate but got error: ${errorValueToString(
+        squiggleResult.value
+      )}`
+    );
+  }
+}
+
 export function failDefault() {
   expect("be reached").toBe("codepath should never");
 }