add a bunch of new tests and add empty test files where missing

docs/src/tests/core/commands/setContent.spec.js

@@ -0,0 +1,21 @@
+context('setContent', () => {
+  before(() => {
+    cy.visit('/examples/basic')
+  })
+
+  it('returns true for the setContent command', () => {
+    cy.get('.ProseMirror').then(([{ editor }]) => {
+      const command = editor.commands.setContent('<p>Example Text</p>')
+
+      expect(command).to.be.eq(true)
+    })
+  })
+
+  it('clears the content when using the setContent command', () => {
+    cy.get('.ProseMirror').then(([{ editor }]) => {
+      editor.commands.setContent('<p>Cindy Lauper</p>')
+
+      expect(editor.getHTML()).to.be.eq('<p>Cindy Lauper</p>')
+    })
+  })
+})