Web IDE markdown preview

17 files changed, 466 insertions, 104 deletions

diff --git a/app/assets/javascripts/ide/components/ide.vue b/app/assets/javascripts/ide/components/ide.vue
index d22869466c9..1c237c0ec97 100644
--- a/app/assets/javascripts/ide/components/ide.vue
+++ b/app/assets/javascripts/ide/components/ide.vue
@@ -3,7 +3,6 @@ import { mapState, mapGetters } from 'vuex';
 import ideSidebar from './ide_side_bar.vue';
 import ideContextbar from './ide_context_bar.vue';
 import repoTabs from './repo_tabs.vue';
-import repoFileButtons from './repo_file_buttons.vue';
 import ideStatusBar from './ide_status_bar.vue';
 import repoEditor from './repo_editor.vue';
 
@@ -12,7 +11,6 @@ export default {
     ideSidebar,
     ideContextbar,
     repoTabs,
-    repoFileButtons,
     ideStatusBar,
     repoEditor,
   },
@@ -70,9 +68,6 @@ export default {
           class="multi-file-edit-pane-content"
           :file="activeFile"
         />
-        <repo-file-buttons
-          :file="activeFile"
-        />
         <ide-status-bar
           :file="activeFile"
         />
diff --git a/app/assets/javascripts/ide/components/ide_file_buttons.vue b/app/assets/javascripts/ide/components/ide_file_buttons.vue
new file mode 100644
index 00000000000..6d07329df71
--- /dev/null
+++ b/app/assets/javascripts/ide/components/ide_file_buttons.vue
@@ -0,0 +1,83 @@
+<script>
+import { __ } from '~/locale';
+import tooltip from '~/vue_shared/directives/tooltip';
+import Icon from '~/vue_shared/components/icon.vue';
+
+export default {
+  components: {
+    Icon,
+  },
+  directives: {
+    tooltip,
+  },
+  props: {
+    file: {
+      type: Object,
+      required: true,
+    },
+  },
+  computed: {
+    showButtons() {
+      return (
+        this.file.rawPath || this.file.blamePath || this.file.commitsPath || this.file.permalink
+      );
+    },
+    rawDownloadButtonLabel() {
+      return this.file.binary ? __('Download') : __('Raw');
+    },
+  },
+};
+</script>
+
+<template>
+  <div
+    v-if="showButtons"
+    class="pull-right ide-btn-group"
+  >
+    <a
+      v-tooltip
+      :href="file.blamePath"
+      :title="__('Blame')"
+      class="btn btn-xs btn-transparent blame"
+    >
+      <icon
+        name="blame"
+        :size="16"
+      />
+    </a>
+    <a
+      v-tooltip
+      :href="file.commitsPath"
+      :title="__('History')"
+      class="btn btn-xs btn-transparent history"
+    >
+      <icon
+        name="history"
+        :size="16"
+      />
+    </a>
+    <a
+      v-tooltip
+      :href="file.permalink"
+      :title="__('Permalink')"
+      class="btn btn-xs btn-transparent permalink"
+    >
+      <icon
+        name="link"
+        :size="16"
+      />
+    </a>
+    <a
+      v-tooltip
+      :href="file.rawPath"
+      target="_blank"
+      class="btn btn-xs btn-transparent prepend-left-10 raw"
+      rel="noopener noreferrer"
+      :title="rawDownloadButtonLabel">
+      <icon
+        name="download"
+        :size="16"
+      />
+    </a>
+  </div>
+</template>
diff --git a/app/assets/javascripts/ide/components/repo_editor.vue b/app/assets/javascripts/ide/components/repo_editor.vue
index b1a16350c19..99423362924 100644
--- a/app/assets/javascripts/ide/components/repo_editor.vue
+++ b/app/assets/javascripts/ide/components/repo_editor.vue
@@ -2,10 +2,16 @@
 /* global monaco */
 import { mapState, mapGetters, mapActions } from 'vuex';
 import flash from '~/flash';
+import ContentViewer from '~/vue_shared/components/content_viewer/content_viewer.vue';
 import monacoLoader from '../monaco_loader';
 import Editor from '../lib/editor';
+import IdeFileButtons from './ide_file_buttons.vue';
 
 export default {
+  components: {
+    ContentViewer,
+    IdeFileButtons,
+  },
   props: {
     file: {
       type: Object,
@@ -18,6 +24,16 @@ export default {
     shouldHideEditor() {
       return this.file && this.file.binary && !this.file.raw;
     },
+    editTabCSS() {
+      return {
+        active: this.file.viewMode === 'edit',
+      };
+    },
+    previewTabCSS() {
+      return {
+        active: this.file.viewMode === 'preview',
+      };
+    },
   },
   watch: {
     file(oldVal, newVal) {
@@ -56,6 +72,7 @@ export default {
       'changeFileContent',
       'setFileLanguage',
       'setEditorPosition',
+      'setFileViewMode',
       'setFileEOL',
       'updateViewer',
       'updateDelayViewerUpdated',
@@ -153,15 +170,47 @@ export default {
     class="blob-viewer-container blob-editor-container"
   >
     <div
-      v-if="shouldHideEditor"
-      v-html="file.html"
-    >
+      class="ide-mode-tabs clearfix"
+      v-if="!shouldHideEditor">
+      <ul class="nav-links pull-left">
+        <li :class="editTabCSS">
+          <a
+            href="javascript:void(0);"
+            role="button"
+            @click.prevent="setFileViewMode({ file, viewMode: 'edit' })">
+            <template v-if="viewer === 'editor'">
+              {{ __('Edit') }}
+            </template>
+            <template v-else>
+              {{ __('Review') }}
+            </template>
+          </a>
+        </li>
+        <li
+          v-if="file.previewMode"
+          :class="previewTabCSS">
+          <a
+            href="javascript:void(0);"
+            role="button"
+            @click.prevent="setFileViewMode({ file, viewMode:'preview' })">
+            {{ file.previewMode.previewTitle }}
+          </a>
+        </li>
+      </ul>
+      <ide-file-buttons
+        :file="file"
+      />
     </div>
     <div
-      v-show="!shouldHideEditor"
+      v-show="!shouldHideEditor && file.viewMode === 'edit'"
       ref="editor"
       class="multi-file-editor-holder"
     >
     </div>
+    <content-viewer
+      v-if="!shouldHideEditor && file.viewMode === 'preview'"
+      :content="file.content || file.raw"
+      :path="file.path"
+      :project-path="file.projectId"/>
   </div>
 </template>
diff --git a/app/assets/javascripts/ide/components/repo_file_buttons.vue b/app/assets/javascripts/ide/components/repo_file_buttons.vue
deleted file mode 100644
index 4ea8cf7504b..00000000000
--- a/app/assets/javascripts/ide/components/repo_file_buttons.vue
+++ /dev/null
@@ -1,61 +0,0 @@
-<script>
-export default {
-  props: {
-    file: {
-      type: Object,
-      required: true,
-    },
-  },
-  computed: {
-    showButtons() {
-      return this.file.rawPath ||
-        this.file.blamePath ||
-        this.file.commitsPath ||
-        this.file.permalink;
-    },
-    rawDownloadButtonLabel() {
-      return this.file.binary ? 'Download' : 'Raw';
-    },
-  },
-};
-</script>
-
-<template>
-  <div
-    v-if="showButtons"
-    class="multi-file-editor-btn-group"
-  >
-    <a
-      :href="file.rawPath"
-      target="_blank"
-      class="btn btn-default btn-sm raw"
-      rel="noopener noreferrer">
-      {{ rawDownloadButtonLabel }}
-    </a>
-
-    <div
-      class="btn-group"
-      role="group"
-      aria-label="File actions"
-    >
-      <a
-        :href="file.blamePath"
-        class="btn btn-default btn-sm blame"
-      >
-        Blame
-      </a>
-      <a
-        :href="file.commitsPath"
-        class="btn btn-default btn-sm history"
-      >
-        History
-      </a>
-      <a
-        :href="file.permalink"
-        class="btn btn-default btn-sm permalink"
-      >
-        Permalink
-      </a>
-    </div>
-  </div>
-</template>
diff --git a/app/assets/javascripts/ide/stores/actions/file.js b/app/assets/javascripts/ide/stores/actions/file.js
index 6b034ea1e82..1a17320a1ea 100644
--- a/app/assets/javascripts/ide/stores/actions/file.js
+++ b/app/assets/javascripts/ide/stores/actions/file.js
@@ -149,6 +149,10 @@ export const setEditorPosition = ({ getters, commit }, { editorRow, editorColumn
   }
 };
 
+export const setFileViewMode = ({ state, commit }, { file, viewMode }) => {
+  commit(types.SET_FILE_VIEWMODE, { file, viewMode });
+};
+
 export const discardFileChanges = ({ state, commit }, path) => {
   const file = state.entries[path];
 
diff --git a/app/assets/javascripts/ide/stores/mutation_types.js b/app/assets/javascripts/ide/stores/mutation_types.js
index ee759bff516..e3f504e5ab0 100644
--- a/app/assets/javascripts/ide/stores/mutation_types.js
+++ b/app/assets/javascripts/ide/stores/mutation_types.js
@@ -38,6 +38,7 @@ export const SET_FILE_BASE_RAW_DATA = 'SET_FILE_BASE_RAW_DATA';
 export const UPDATE_FILE_CONTENT = 'UPDATE_FILE_CONTENT';
 export const SET_FILE_LANGUAGE = 'SET_FILE_LANGUAGE';
 export const SET_FILE_POSITION = 'SET_FILE_POSITION';
+export const SET_FILE_VIEWMODE = 'SET_FILE_VIEWMODE';
 export const SET_FILE_EOL = 'SET_FILE_EOL';
 export const DISCARD_FILE_CHANGES = 'DISCARD_FILE_CHANGES';
 export const ADD_FILE_TO_CHANGED = 'ADD_FILE_TO_CHANGED';
diff --git a/app/assets/javascripts/ide/stores/mutations/file.js b/app/assets/javascripts/ide/stores/mutations/file.js
index 926b6f66d78..6a143e518f9 100644
--- a/app/assets/javascripts/ide/stores/mutations/file.js
+++ b/app/assets/javascripts/ide/stores/mutations/file.js
@@ -42,6 +42,7 @@ export default {
       renderError: data.render_error,
       raw: null,
       baseRaw: null,
+      html: data.html,
     });
   },
   [types.SET_FILE_RAW_DATA](state, { file, raw }) {
@@ -83,6 +84,11 @@ export default {
       mrChange,
     });
   },
+  [types.SET_FILE_VIEWMODE](state, { file, viewMode }) {
+    Object.assign(state.entries[file.path], {
+      viewMode,
+    });
+  },
   [types.DISCARD_FILE_CHANGES](state, path) {
     Object.assign(state.entries[path], {
       content: state.entries[path].raw,
diff --git a/app/assets/javascripts/ide/stores/utils.js b/app/assets/javascripts/ide/stores/utils.js
index 63e4de3b17d..4befcc501ef 100644
--- a/app/assets/javascripts/ide/stores/utils.js
+++ b/app/assets/javascripts/ide/stores/utils.js
@@ -38,6 +38,8 @@ export const dataStructure = () => ({
   editorColumn: 1,
   fileLanguage: '',
   eol: '',
+  viewMode: 'edit',
+  previewMode: null,
 });
 
 export const decorateData = entity => {
@@ -57,8 +59,9 @@ export const decorateData = entity => {
     changed = false,
     parentTreeUrl = '',
     base64 = false,
-
+    previewMode,
     file_lock,
+    html,
   } = entity;
 
   return {
@@ -79,8 +82,9 @@ export const decorateData = entity => {
     renderError,
     content,
     base64,
-
+    previewMode,
     file_lock,
+    html,
   };
 };
 
diff --git a/app/assets/javascripts/ide/stores/workers/files_decorator_worker.js b/app/assets/javascripts/ide/stores/workers/files_decorator_worker.js
index a4cd1ab099f..a1673276900 100644
--- a/app/assets/javascripts/ide/stores/workers/files_decorator_worker.js
+++ b/app/assets/javascripts/ide/stores/workers/files_decorator_worker.js
@@ -1,14 +1,8 @@
+import { viewerInformationForPath } from '~/vue_shared/components/content_viewer/lib/viewer_utils';
 import { decorateData, sortTree } from '../utils';
 
 self.addEventListener('message', e => {
-  const {
-    data,
-    projectId,
-    branchId,
-    tempFile = false,
-    content = '',
-    base64 = false,
-  } = e.data;
+  const { data, projectId, branchId, tempFile = false, content = '', base64 = false } = e.data;
 
   const treeList = [];
   let file;
@@ -19,9 +13,7 @@ self.addEventListener('message', e => {
     if (pathSplit.length > 0) {
       pathSplit.reduce((pathAcc, folderName) => {
         const parentFolder = acc[pathAcc[pathAcc.length - 1]];
-        const folderPath = `${
-          parentFolder ? `${parentFolder.path}/` : ''
-        }${folderName}`;
+        const folderPath = `${parentFolder ? `${parentFolder.path}/` : ''}${folderName}`;
         const foundEntry = acc[folderPath];
 
         if (!foundEntry) {
@@ -33,9 +25,7 @@ self.addEventListener('message', e => {
             path: folderPath,
             url: `/${projectId}/tree/${branchId}/${folderPath}/`,
             type: 'tree',
-            parentTreeUrl: parentFolder
-              ? parentFolder.url
-              : `/${projectId}/tree/${branchId}/`,
+            parentTreeUrl: parentFolder ? parentFolder.url : `/${projectId}/tree/${branchId}/`,
             tempFile,
             changed: tempFile,
             opened: tempFile,
@@ -70,13 +60,12 @@ self.addEventListener('message', e => {
         path,
         url: `/${projectId}/blob/${branchId}/${path}`,
         type: 'blob',
-        parentTreeUrl: fileFolder
-          ? fileFolder.url
-          : `/${projectId}/blob/${branchId}`,
+        parentTreeUrl: fileFolder ? fileFolder.url : `/${projectId}/blob/${branchId}`,
         tempFile,
         changed: tempFile,
         content,
         base64,
+        previewMode: viewerInformationForPath(blobName),
       });
 
       Object.assign(acc, {
diff --git a/app/assets/javascripts/vue_shared/components/content_viewer/content_viewer.vue b/app/assets/javascripts/vue_shared/components/content_viewer/content_viewer.vue
new file mode 100644
index 00000000000..fb8ccea91c7
--- /dev/null
+++ b/app/assets/javascripts/vue_shared/components/content_viewer/content_viewer.vue
@@ -0,0 +1,43 @@
+<script>
+import { viewerInformationForPath } from './lib/viewer_utils';
+import MarkdownViewer from './viewers/markdown_viewer.vue';
+
+export default {
+  props: {
+    content: {
+      type: String,
+      required: true,
+    },
+    path: {
+      type: String,
+      required: true,
+    },
+    projectPath: {
+      type: String,
+      required: false,
+      default: '',
+    },
+  },
+  computed: {
+    viewer() {
+      const previewInfo = viewerInformationForPath(this.path);
+      switch (previewInfo.id) {
+        case 'markdown':
+          return MarkdownViewer;
+        default:
+          return null;
+      }
+    },
+  },
+};
+</script>
+
+<template>
+  <div class="preview-container">
+    <component
+      :is="viewer"
+      :project-path="projectPath"
+      :content="content"
+    />
+  </div>
+</template>
diff --git a/app/assets/javascripts/vue_shared/components/content_viewer/lib/viewer_utils.js b/app/assets/javascripts/vue_shared/components/content_viewer/lib/viewer_utils.js
new file mode 100644
index 00000000000..4f2e1e47dd1
--- /dev/null
+++ b/app/assets/javascripts/vue_shared/components/content_viewer/lib/viewer_utils.js
@@ -0,0 +1,23 @@
+const viewers = {
+  markdown: {
+    id: 'markdown',
+    previewTitle: 'Preview Markdown',
+  },
+};
+
+const fileNameViewers = {};
+const fileExtensionViewers = {
+  md: 'markdown',
+  markdown: 'markdown',
+};
+
+export function viewerInformationForPath(path) {
+  if (!path) return null;
+  const name = path.split('/').pop();
+  const viewerName =
+    fileNameViewers[name] || fileExtensionViewers[name ? name.split('.').pop() : ''] || '';
+
+  return viewers[viewerName];
+}
+
+export default viewers;
diff --git a/app/assets/javascripts/vue_shared/components/content_viewer/viewers/markdown_viewer.vue b/app/assets/javascripts/vue_shared/components/content_viewer/viewers/markdown_viewer.vue
new file mode 100644
index 00000000000..09e0094054d
--- /dev/null
+++ b/app/assets/javascripts/vue_shared/components/content_viewer/viewers/markdown_viewer.vue
@@ -0,0 +1,90 @@
+<script>
+import axios from '~/lib/utils/axios_utils';
+import { __ } from '~/locale';
+import $ from 'jquery';
+import SkeletonLoadingContainer from '~/vue_shared/components/skeleton_loading_container.vue';
+
+const CancelToken = axios.CancelToken;
+let axiosSource;
+
+export default {
+  components: {
+    SkeletonLoadingContainer,
+  },
+  props: {
+    content: {
+      type: String,
+      required: true,
+    },
+    projectPath: {
+      type: String,
+      required: true,
+    },
+  },
+  data() {
+    return {
+      previewContent: null,
+      isLoading: false,
+    };
+  },
+  watch: {
+    content() {
+      this.previewContent = null;
+    },
+  },
+  created() {
+    axiosSource = CancelToken.source();
+    this.fetchMarkdownPreview();
+  },
+  updated() {
+    this.fetchMarkdownPreview();
+  },
+  destroyed() {
+    if (this.isLoading) axiosSource.cancel('Cancelling Preview');
+  },
+  methods: {
+    fetchMarkdownPreview() {
+      if (this.content && this.previewContent === null) {
+        this.isLoading = true;
+        const postBody = {
+          text: this.content,
+        };
+        const postOptions = {
+          cancelToken: axiosSource.token,
+        };
+
+        axios
+          .post(
+            `${gon.relative_url_root}/${this.projectPath}/preview_markdown`,
+            postBody,
+            postOptions,
+          )
+          .then(({ data }) => {
+            this.previewContent = data.body;
+            this.isLoading = false;
+
+            this.$nextTick(() => {
+              $(this.$refs['markdown-preview']).renderGFM();
+            });
+          })
+          .catch(() => {
+            this.previewContent = __('An error occurred while fetching markdown preview');
+            this.isLoading = false;
+          });
+      }
+    },
+  },
+};
+</script>
+
+<template>
+  <div
+    ref="markdown-preview"
+    class="md md-previewer">
+    <skeleton-loading-container v-if="isLoading" />
+    <div
+      v-else
+      v-html="previewContent">
+    </div>
+  </div>
+</template>
diff --git a/app/assets/stylesheets/pages/repo.scss b/app/assets/stylesheets/pages/repo.scss
index 1f6f7138e1f..8cc5c8fc877 100644
--- a/app/assets/stylesheets/pages/repo.scss
+++ b/app/assets/stylesheets/pages/repo.scss
@@ -308,14 +308,34 @@
   height: 100%;
 }
 
-.multi-file-editor-btn-group {
-  padding: $gl-bar-padding $gl-padding;
-  border-top: 1px solid $white-dark;
+.preview-container {
+  height: 100%;
+  overflow: auto;
+
+  .md-previewer {
+    padding: $gl-padding;
+  }
+}
+
+.ide-mode-tabs {
   border-bottom: 1px solid $white-dark;
-  background: $white-light;
+
+  .nav-links {
+    border-bottom: 0;
+
+    li a {
+      padding: $gl-padding-8 $gl-padding;
+      line-height: $gl-btn-line-height;
+    }
+  }
+}
+
+.ide-btn-group {
+  padding: $gl-padding-4 $gl-vert-padding;
 }
 
 .ide-status-bar {
+  border-top: 1px solid $white-dark;
   padding: $gl-bar-padding $gl-padding;
   background: $white-light;
   display: flex;
diff --git a/spec/javascripts/ide/components/repo_file_buttons_spec.js b/spec/javascripts/ide/components/ide_file_buttons_spec.js
index c86bdb132b4..8ac8d1b2acf 100644
--- a/spec/javascripts/ide/components/repo_file_buttons_spec.js
+++ b/spec/javascripts/ide/components/ide_file_buttons_spec.js
@@ -1,5 +1,5 @@
 import Vue from 'vue';
-import repoFileButtons from '~/ide/components/repo_file_buttons.vue';
+import repoFileButtons from '~/ide/components/ide_file_buttons.vue';
 import createVueComponent from '../../helpers/vue_mount_component_helper';
 import { file } from '../helpers';
 
@@ -23,7 +23,7 @@ describe('RepoFileButtons', () => {
     vm.$destroy();
   });
 
-  it('renders Raw, Blame, History, Permalink and Preview toggle', done => {
+  it('renders Raw, Blame, History and Permalink', done => {
     vm = createComponent();
 
     vm.$nextTick(() => {
@@ -32,16 +32,30 @@ describe('RepoFileButtons', () => {
       const history = vm.$el.querySelector('.history');
 
       expect(raw.href).toMatch(`/${activeFile.rawPath}`);
-      expect(raw.textContent.trim()).toEqual('Raw');
+      expect(raw.getAttribute('data-original-title')).toEqual('Raw');
       expect(blame.href).toMatch(`/${activeFile.blamePath}`);
-      expect(blame.textContent.trim()).toEqual('Blame');
+      expect(blame.getAttribute('data-original-title')).toEqual('Blame');
       expect(history.href).toMatch(`/${activeFile.commitsPath}`);
-      expect(history.textContent.trim()).toEqual('History');
-      expect(vm.$el.querySelector('.permalink').textContent.trim()).toEqual(
+      expect(history.getAttribute('data-original-title')).toEqual('History');
+      expect(vm.$el.querySelector('.permalink').getAttribute('data-original-title')).toEqual(
         'Permalink',
       );
 
       done();
     });
   });
+
+  it('renders Download', done => {
+    activeFile.binary = true;
+    vm = createComponent();
+
+    vm.$nextTick(() => {
+      const raw = vm.$el.querySelector('.raw');
+
+      expect(raw.href).toMatch(`/${activeFile.rawPath}`);
+      expect(raw.getAttribute('data-original-title')).toEqual('Download');
+
+      done();
+    });
+  });
 });
diff --git a/spec/javascripts/ide/components/repo_editor_spec.js b/spec/javascripts/ide/components/repo_editor_spec.js
index 9d3fa1280f4..e79b85050b2 100644
--- a/spec/javascripts/ide/components/repo_editor_spec.js
+++ b/spec/javascripts/ide/components/repo_editor_spec.js
@@ -19,7 +19,6 @@ describe('RepoEditor', () => {
 
     f.active = true;
     f.tempFile = true;
-    f.html = 'testing';
     vm.$store.state.openFiles.push(f);
     vm.$store.state.entries[f.path] = f;
     vm.monaco = true;
@@ -47,6 +46,61 @@ describe('RepoEditor', () => {
     });
   });
 
+  it('renders only an edit tab', done => {
+    Vue.nextTick(() => {
+      const tabs = vm.$el.querySelectorAll('.ide-mode-tabs .nav-links li');
+      expect(tabs.length).toBe(1);
+      expect(tabs[0].textContent.trim()).toBe('Edit');
+
+      done();
+    });
+  });
+
+  describe('when file is markdown', () => {
+    beforeEach(done => {
+      vm.file.previewMode = {
+        id: 'markdown',
+        previewTitle: 'Preview Markdown',
+      };
+
+      vm.$nextTick(done);
+    });
+
+    it('renders an Edit and a Preview Tab', done => {
+      Vue.nextTick(() => {
+        const tabs = vm.$el.querySelectorAll('.ide-mode-tabs .nav-links li');
+        expect(tabs.length).toBe(2);
+        expect(tabs[0].textContent.trim()).toBe('Edit');
+        expect(tabs[1].textContent.trim()).toBe('Preview Markdown');
+
+        done();
+      });
+    });
+  });
+
+  describe('when file is markdown and viewer mode is review', () => {
+    beforeEach(done => {
+      vm.file.previewMode = {
+        id: 'markdown',
+        previewTitle: 'Preview Markdown',
+      };
+      vm.$store.state.viewer = 'diff';
+
+      vm.$nextTick(done);
+    });
+
+    it('renders an Edit and a Preview Tab', done => {
+      Vue.nextTick(() => {
+        const tabs = vm.$el.querySelectorAll('.ide-mode-tabs .nav-links li');
+        expect(tabs.length).toBe(2);
+        expect(tabs[0].textContent.trim()).toBe('Review');
+        expect(tabs[1].textContent.trim()).toBe('Preview Markdown');
+
+        done();
+      });
+    });
+  });
+
   describe('when open file is binary and not raw', () => {
     beforeEach(done => {
       vm.file.binary = true;
@@ -57,10 +111,6 @@ describe('RepoEditor', () => {
     it('does not render the IDE', () => {
       expect(vm.shouldHideEditor).toBeTruthy();
     });
-
-    it('shows activeFile html', () => {
-      expect(vm.$el.textContent).toContain('testing');
-    });
   });
 
   describe('createEditorInstance', () => {
diff --git a/spec/javascripts/ide/stores/mutations/file_spec.js b/spec/javascripts/ide/stores/mutations/file_spec.js
index 88285ee409f..bf9d5166d0a 100644
--- a/spec/javascripts/ide/stores/mutations/file_spec.js
+++ b/spec/javascripts/ide/stores/mutations/file_spec.js
@@ -194,6 +194,17 @@ describe('IDE store file mutations', () => {
     });
   });
 
+  describe('SET_FILE_VIEWMODE', () => {
+    it('updates file view mode', () => {
+      mutations.SET_FILE_VIEWMODE(localState, {
+        file: localFile,
+        viewMode: 'preview',
+      });
+
+      expect(localFile.viewMode).toBe('preview');
+    });
+  });
+
   describe('ADD_PENDING_TAB', () => {
     beforeEach(() => {
       const f = {
diff --git a/spec/javascripts/vue_shared/components/content_viewer/content_viewer_spec.js b/spec/javascripts/vue_shared/components/content_viewer/content_viewer_spec.js
new file mode 100644
index 00000000000..c7c454a0b45
--- /dev/null
+++ b/spec/javascripts/vue_shared/components/content_viewer/content_viewer_spec.js
@@ -0,0 +1,41 @@
+import Vue from 'vue';
+import MockAdapter from 'axios-mock-adapter';
+import axios from '~/lib/utils/axios_utils';
+import contentViewer from '~/vue_shared/components/content_viewer/content_viewer.vue';
+import mountComponent from 'spec/helpers/vue_mount_component_helper';
+
+describe('ContentViewer', () => {
+  let vm;
+  let mock;
+
+  function createComponent(props) {
+    const ContentViewer = Vue.extend(contentViewer);
+    vm = mountComponent(ContentViewer, props);
+  }
+
+  afterEach(() => {
+    vm.$destroy();
+    if (mock) mock.restore();
+  });
+
+  it('markdown preview renders + loads rendered markdown from server', done => {
+    mock = new MockAdapter(axios);
+    mock.onPost(`${gon.relative_url_root}/testproject/preview_markdown`).reply(200, {
+      body: '<b>testing</b>',
+    });
+
+    createComponent({
+      path: 'test.md',
+      content: '*  Test',
+      projectPath: 'testproject',
+    });
+
+    const previewContainer = vm.$el.querySelector('.md-previewer');
+
+    setTimeout(() => {
+      expect(previewContainer.textContent).toContain('testing');
+
+      done();
+    });
+  });
+});