Add cypress example for data sources.

cypress/integration/elm-pages-dev-base-path.spec.js

@@ -0,0 +1,44 @@
+context("dev server with base path", () => {
+  it("404 message", () => {
+    cy.visit("/qwer/asdf", { failOnStatusCode: false });
+    cy.contains("No route found for /asdf");
+  });
+
+  it("navigates to root page", () => {
+    cy.visit("/qwer/");
+    cy.contains("This is the index page");
+  });
+
+  it("loads file data sources", () => {
+    cy.writeFile(
+      "examples/end-to-end/my-json-data.json",
+      JSON.stringify({
+        greeting: "Hello, World!",
+      })
+    );
+    cy.visit("/qwer/file-data");
+
+    cy.contains("Greeting: Hello, World!");
+    cy.writeFile(
+      "examples/end-to-end/my-json-data.json",
+      JSON.stringify({
+        greeting: "Goodbye, World!",
+      })
+    );
+    cy.contains("Greeting: Goodbye, World!");
+    cy.writeFile(
+      "examples/end-to-end/my-json-data.json",
+      JSON.stringify({
+        greeting: null,
+      })
+    );
+
+    cy.contains(`I encountered some errors while decoding this JSON:
+
+At path /jsonFile/greeting
+
+  I expected a string here, but instead found this value:
+
+    null`);
+  });
+});

examples/end-to-end/src/Site.elm

@@ -52,7 +52,7 @@ manifest static =
     Manifest.init
         { name = static.siteName
         , description = "elm-pages - " ++ tagline
-        , startUrl = Route.Slide__Number_ { number = "1" } |> Route.toPath
+        , startUrl = Route.Index |> Route.toPath
         , icons =
             [ icon webp 192
             , icon webp 512