Radio: Extract validation out of scoring

.changeset/spotty-moles-reply.md

@@ -0,0 +1,5 @@
+---
+"@khanacademy/perseus": minor
+---
+
+Introduces a validation function for the radio widget (extracted from the scoring function), though not all validation logic can be extracted.

packages/perseus/src/widgets/radio/score-radio.test.ts

@@ -8,25 +8,6 @@ import type {
 } from "../../validation.types";
 
 describe("scoreRadio", () => {
-    it("is invalid when no options are selected", () => {
-        const userInput: PerseusRadioUserInput = {
-            choicesSelected: [false, false, false, false],
-        };
-
-        const rubric: PerseusRadioRubric = {
-            choices: [
-                {content: "Choice 1"},
-                {content: "Choice 2"},
-                {content: "Choice 3"},
-                {content: "Choice 4"},
-            ],
-        };
-
-        const result = scoreRadio(userInput, rubric, mockStrings);
-
-        expect(result).toHaveInvalidInput();
-    });
-
     it("is invalid when number selected does not match number correct", () => {
         const userInput: PerseusRadioUserInput = {
             choicesSelected: [true, false, false, false],
@@ -41,9 +22,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveInvalidInput();
+        expect(score).toHaveInvalidInput();
     });
 
     it("is invalid when none of the above and an answer are both selected", () => {
@@ -65,9 +46,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveInvalidInput();
+        expect(score).toHaveInvalidInput();
     });
 
     it("can handle single correct answer", () => {
@@ -84,9 +65,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveBeenAnsweredCorrectly();
+        expect(score).toHaveBeenAnsweredCorrectly();
     });
 
     it("can handle single incorrect answer", () => {
@@ -103,9 +84,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveBeenAnsweredIncorrectly();
+        expect(score).toHaveBeenAnsweredIncorrectly();
     });
 
     it("can handle multiple correct answer", () => {
@@ -122,9 +103,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveBeenAnsweredCorrectly();
+        expect(score).toHaveBeenAnsweredCorrectly();
     });
 
     it("can handle multiple incorrect answer", () => {
@@ -141,9 +122,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveBeenAnsweredIncorrectly();
+        expect(score).toHaveBeenAnsweredIncorrectly();
     });
 
     it("can handle none of the above correct answer", () => {
@@ -161,9 +142,9 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveBeenAnsweredCorrectly();
+        expect(score).toHaveBeenAnsweredCorrectly();
     });
 
     it("can handle none of the above incorrect answer", () => {
@@ -181,8 +162,8 @@ describe("scoreRadio", () => {
             ],
         };
 
-        const result = scoreRadio(userInput, rubric, mockStrings);
+        const score = scoreRadio(userInput, rubric, mockStrings);
 
-        expect(result).toHaveBeenAnsweredIncorrectly();
+        expect(score).toHaveBeenAnsweredIncorrectly();
     });
 });

packages/perseus/src/widgets/radio/score-radio.ts

@@ -1,3 +1,5 @@
+import validateRadio from "./validate-radio";
+
 import type {PerseusStrings} from "../../strings";
 import type {PerseusScore} from "../../types";
 import type {
@@ -10,17 +12,15 @@ function scoreRadio(
     rubric: PerseusRadioRubric,
     strings: PerseusStrings,
 ): PerseusScore {
+    const validationError = validateRadio(userInput);
+    if (validationError) {
+        return validationError;
+    }
+
     const numSelected = userInput.choicesSelected.reduce((sum, selected) => {
         return sum + (selected ? 1 : 0);
     }, 0);
 
-    if (numSelected === 0) {
-        return {
-            type: "invalid",
-            message: null,
-        };
-    }
-
     const numCorrect: number = rubric.choices.reduce((sum, currentChoice) => {
         return currentChoice.correct ? sum + 1 : sum;
     }, 0);

packages/perseus/src/widgets/radio/validate-radio.test.ts

@@ -0,0 +1,25 @@
+import validateRadio from "./validate-radio";
+
+import type {PerseusRadioUserInput} from "../../validation.types";
+
+describe("validateRadio", () => {
+    it("is invalid when no options are selected", () => {
+        const userInput: PerseusRadioUserInput = {
+            choicesSelected: [false, false, false, false],
+        };
+
+        const validationError = validateRadio(userInput);
+
+        expect(validationError).toHaveInvalidInput();
+    });
+
+    it("returns null when validation passes", () => {
+        const userInput: PerseusRadioUserInput = {
+            choicesSelected: [true, false, false, false],
+        };
+
+        const validationError = validateRadio(userInput);
+
+        expect(validationError).toBeNull();
+    });
+});

packages/perseus/src/widgets/radio/validate-radio.ts

@@ -0,0 +1,29 @@
+import type {PerseusScore} from "../../types";
+import type {PerseusRadioUserInput} from "../../validation.types";
+
+/**
+ * Checks if the user has selected at least one option. Additional validation
+ * is done in scoreRadio to check if the number of selected options is correct
+ * and if the user has selected both a correct option and the "none of the above"
+ * option.
+ * @param userInput
+ * @see `scoreRadio` for the additional validation logic and the scoring logic.
+ */
+function validateRadio(
+    userInput: PerseusRadioUserInput,
+): Extract<PerseusScore, {type: "invalid"}> | null {
+    const numSelected = userInput.choicesSelected.reduce((sum, selected) => {
+        return sum + (selected ? 1 : 0);
+    }, 0);
+
+    if (numSelected === 0) {
+        return {
+            type: "invalid",
+            message: null,
+        };
+    }
+
+    return null;
+}
+
+export default validateRadio;