diff --git a/.github/workflows/solutions.yml b/.github/workflows/solutions.yml
index 6eb097e3..c6c6ba66 100644
--- a/.github/workflows/solutions.yml
+++ b/.github/workflows/solutions.yml
@@ -25,10 +25,10 @@ jobs:
         run: ./scripts/copy-solutions.sh
         shell: bash
       - name: Run changed solutions in project directories
-        if: ${{ steps.changed-files.outputs.all_changed_files != '' }}
-        run: npx zx ./scripts/changed-solutions.mjs "test:solutions" ${{ steps.changed-files.outputs.all_changed_files }}
+        if: ${{ steps.changed-files.outputs.all_modified_files != '' }}
+        run: npx zx ./scripts/changed-solutions.mjs "test:solutions" ${{ steps.changed-files.outputs.all_modified_files }}
         shell: bash
       - name: Run all solutions tests
-        if: ${{ steps.changed-files.outputs.all_changed_files == '' }}
+        if: ${{ steps.changed-files.outputs.all_modified_files == '' }}
         run: ./scripts/check-solutions.sh "test:solutions"
         shell: bash
diff --git a/.github/workflows/test.yml b/.github/workflows/test.yml
index 089e2022..a7f3a6fb 100644
--- a/.github/workflows/test.yml
+++ b/.github/workflows/test.yml
@@ -25,10 +25,10 @@ jobs:
         run: ./scripts/copy-solutions.sh
         shell: bash
       - name: Run test in project directories
-        if: ${{ steps.changed-files.outputs.all_changed_files != '' }}
-        run: npx zx ./scripts/changed-solutions.mjs test ${{ steps.changed-files.outputs.all_changed_files }}
+        if: ${{ steps.changed-files.outputs.all_modified_files != '' }}
+        run: npx zx ./scripts/changed-solutions.mjs test ${{ steps.changed-files.outputs.all_modified_files }}
         shell: bash
       - name: Run test in all project directories
-        if: ${{ steps.changed-files.outputs.all_changed_files == '' }}
+        if: ${{ steps.changed-files.outputs.all_modified_files == '' }}
         run: ./scripts/check-solutions.sh "test"
         shell: bash
diff --git a/.github/workflows/tsc.yml b/.github/workflows/tsc.yml
index 961a05a1..dc0b4d70 100644
--- a/.github/workflows/tsc.yml
+++ b/.github/workflows/tsc.yml
@@ -25,10 +25,10 @@ jobs:
         run: ./scripts/copy-solutions.sh
         shell: bash
       - name: Run tsc in project directories
-        if: ${{ steps.changed-files.outputs.all_changed_files != '' }}
-        run: npx zx ./scripts/changed-solutions.mjs tsc ${{ steps.changed-files.outputs.all_changed_files }}
+        if: ${{ steps.changed-files.outputs.all_modified_files != '' }}
+        run: npx zx ./scripts/changed-solutions.mjs tsc ${{ steps.changed-files.outputs.all_modified_files }}
         shell: bash
       - name: Run tsc in all project directories
-        if: ${{ steps.changed-files.outputs.all_changed_files == '' }}
+        if: ${{ steps.changed-files.outputs.all_modified_files == '' }}
         run: ./scripts/check-solutions.sh "tsc"
         shell: bash
diff --git a/test/files.test.ts b/test/files.test.ts
index 07af94aa..cd71e312 100644
--- a/test/files.test.ts
+++ b/test/files.test.ts
@@ -54,6 +54,28 @@ for (const chapterSlug of fs.readdirSync("projects")) {
 					testAppetizerProject();
 				}
 
+				function projectUsesJest() {
+					const packageData = readFileAsJSON(
+						`${chapterDirectory}/${projectSlug}/package.json`,
+					) as PackageData;
+
+					return packageData.scripts.test === "jest";
+				}
+
+				function testContainsTestFile(directorySlug: string) {
+					test("test file", () => {
+						const directoryContents = fs.readdirSync(
+							`${chapterDirectory}/${projectSlug}/${directorySlug}`,
+						);
+
+						expect(
+							directoryContents.filter((fileName) =>
+								fileName.includes(".test."),
+							),
+						).not.toEqual([]);
+					});
+				}
+
 				function testAppetizerProject() {
 					const stepSlugs = fs
 						.readdirSync(`${chapterDirectory}/${projectSlug}`)
@@ -115,8 +137,14 @@ npm run test -- 1 --watch
 						});
 					}
 
+					const usesJest = projectUsesJest();
+
 					for (const stepSlug of stepSlugs) {
 						describe(stepSlug, () => {
+							if (usesJest) {
+								testContainsTestFile(stepSlug);
+							}
+
 							test("tsconfig.json", () => {
 								const tsconfigData = readFileAsJSON(
 									`${chapterDirectory}/${projectSlug}/${stepSlug}/tsconfig.json`,
@@ -145,6 +173,10 @@ npm run test -- 1 --watch
 
 					testPackageJson();
 
+					if (projectUsesJest()) {
+						testContainsTestFile("src");
+					}
+
 					test("README.md", () => {
 						const contents = fs
 							.readFileSync(`${chapterDirectory}/${projectSlug}/README.md`)