Make Action Parameters attributes case-insensitive (#571)

Even though this is not the "recommended way" to specify the data 
attributes for the params it's to match the existing behaviour of 
Actions, Controllers, Targets and Values.

Resolves #561

src/core/action.ts

@@ -31,7 +31,7 @@ export class Action {
 
   get params() {
     const params:{ [key: string]: any } = {}
-    const pattern = new RegExp(`^data-${this.identifier}-(.+)-param$`)
+    const pattern = new RegExp(`^data-${this.identifier}-(.+)-param$`, "i")
 
     for (const { name, value } of Array.from(this.element.attributes)) {
       const match = name.match(pattern)

src/tests/modules/core/action_params_case_insensitive_tests.ts

@@ -0,0 +1,62 @@
+import ActionParamsTests from "./action_params_tests"
+
+export default class ActionParamsCaseInsensitiveTests extends ActionParamsTests {
+  identifier = ["CamelCase", "AnotherOne"]
+  fixtureHTML = `
+    <div data-controller="CamelCase AnotherOne">
+      <button data-CamelCase-id-param="123"
+              data-CamelCase-multi-word-example-param="/path"
+              data-CamelCase-active-param="true"
+              data-CamelCase-inactive-param="false"
+              data-CamelCase-empty-param=""
+              data-CamelCase-payload-param='${JSON.stringify({value: 1})}'
+              data-CamelCase-param-something="not-reported"
+              data-Something-param="not-reported"
+              data-AnotherOne-id-param="234">
+        <div id="nested"></div>
+      </button>
+    </div>
+    <div id="outside"></div>
+  `
+  expectedParamsForCamelCase = {
+    id: 123,
+    multiWordExample: "/path",
+    payload: {
+      value: 1
+    },
+    active: true,
+    empty: "",
+    inactive: false
+  }
+
+  async "test clicking on the element does return its params"() {
+    this.actionValue = "click->CamelCase#log"
+    await this.nextFrame
+    await this.triggerEvent(this.buttonElement, "click")
+
+    this.assertActions(
+      { identifier: "CamelCase", params: this.expectedParamsForCamelCase },
+    )
+  }
+
+  async "test global event return element params where the action is defined"() {
+    this.actionValue = "keydown@window->CamelCase#log"
+    await this.nextFrame
+    await this.triggerEvent("#outside", "keydown")
+
+    this.assertActions(
+      { identifier: "CamelCase", params: this.expectedParamsForCamelCase },
+    )
+  }
+
+  async "test passing params to namespaced controller"() {
+    this.actionValue = "click->CamelCase#log click->AnotherOne#log2"
+    await this.nextFrame
+    await this.triggerEvent(this.buttonElement, "click")
+
+    this.assertActions(
+      { identifier: "CamelCase", params: this.expectedParamsForCamelCase },
+      { identifier: "AnotherOne", params: { id: 234 } },
+    )
+  }
+}

src/tests/modules/core/action_params_tests.ts

@@ -69,10 +69,10 @@ export default class ActionParamsTests extends LogControllerTestCase {
       { identifier: "c", params: this.expectedParamsForC },
     )
 
-    await this.buttonElement.setAttribute("data-c-id-param", "234")
-    await this.buttonElement.setAttribute("data-c-new-param", "new")
-    await this.buttonElement.removeAttribute("data-c-payload-param")
-    await this.triggerEvent(this.buttonElement, "click")
+    this.buttonElement.setAttribute("data-c-id-param", "234")
+    this.buttonElement.setAttribute("data-c-new-param", "new")
+    this.buttonElement.removeAttribute("data-c-payload-param")
+    this.triggerEvent(this.buttonElement, "click")
 
     this.assertActions(
       { identifier: "c", params: this.expectedParamsForC },