diff --git a/airlock/file_browser_api.py b/airlock/file_browser_api.py
index 5e999d5c..8e4c30b9 100644
--- a/airlock/file_browser_api.py
+++ b/airlock/file_browser_api.py
@@ -47,18 +47,6 @@ class PathNotFound(Exception):
     # but this allow it to be overridden.
     display_text: str = None
 
-    DISPLAY_TYPES = {
-        "html": "iframe",
-        "jpeg": "image",
-        "jpg": "image",
-        "png": "image",
-        "svg": "image",
-        "csv": "table",
-        "tsv": "table",
-        "txt": "preformatted",
-        "log": "preformatted",
-    }
-
     def __post_init__(self):
         # ensure is UrlPath
         self.relpath = UrlPath(self.relpath)
@@ -121,9 +109,6 @@ def suffix(self):
     def file_type(self):
         return self.suffix().lstrip(".")
 
-    def display_type(self):
-        return self.DISPLAY_TYPES.get(self.file_type(), "preformatted")
-
     def breadcrumbs(self):
         item = self
         crumbs = [item]
diff --git a/airlock/templates/file_browser/contents.html b/airlock/templates/file_browser/contents.html
index 96f7bced..6cfdad05 100644
--- a/airlock/templates/file_browser/contents.html
+++ b/airlock/templates/file_browser/contents.html
@@ -21,66 +21,53 @@
 
   {% else %}
     {% fragment as add_button %}
-      {% if context == "workspace" %}
-        {% if form %}
-          {% #modal id="addRequestFile" button_text="Add File to Request" variant="success" %}
-            {% #card container=True title="Add a file" %}
-              <form action="{{ request_file_url }}" method="POST" aria-label="add-file-form">
-                {% csrf_token %}
-                {% form_select class="w-full max-w-lg mx-auto" label="Select a file group" field=form.filegroup choices=form.filegroup.field.choices %}
-                {% form_input class="w-full max-w-lg mx-auto" label="Or create a new file group" field=form.new_filegroup %}
-                <input type=hidden name="path" value="{{ path_item.relpath }}"/>
-                <div class="mt-2">
-                  {% #button type="submit" variant="success" id="add-file-button" %}Add File to Request{% /button %}
-                  {% #button variant="danger" type="cancel" %}Cancel{% /button %}
-                </div>
-              </form>
-            {% /card %}
-          {% /modal %}
-        {% elif file_in_request %}
-          {% #button type="button" disabled=True tooltip="This file has already been added to the current request" id="add-file-modal-button-disabled" %}
-            Add File to Request
-          {% /button %}
-        {% else %}
-          {% #button type="button" disabled=True tooltip="You do not have permission to add this file to a request" id="add-file-modal-button-disabled" %}
-            Add File to Request
-          {% /button %}
+      <div class="flex items-center gap-2">
+        {% if context == "workspace" %}
+          {% if form %}
+            {% #modal id="addRequestFile" button_text="Add File to Request" variant="success" %}
+              {% #card container=True title="Add a file" %}
+                <form action="{{ request_file_url }}" method="POST" aria-label="add-file-form">
+                  {% csrf_token %}
+                  {% form_select class="w-full max-w-lg mx-auto" label="Select a file group" field=form.filegroup choices=form.filegroup.field.choices %}
+                  {% form_input class="w-full max-w-lg mx-auto" label="Or create a new file group" field=form.new_filegroup %}
+                  <input type=hidden name="path" value="{{ path_item.relpath }}"/>
+                  <div class="mt-2">
+                    {% #button type="submit" variant="success" id="add-file-button" %}Add File to Request{% /button %}
+                    {% #button variant="danger" type="cancel" %}Cancel{% /button %}
+                  </div>
+                </form>
+              {% /card %}
+            {% /modal %}
+          {% elif file_in_request %}
+            {% #button type="button" disabled=True tooltip="This file has already been added to the current request" id="add-file-modal-button-disabled" %}
+              Add File to Request
+            {% /button %}
+          {% else %}
+            {% #button type="button" disabled=True tooltip="You do not have permission to add this file to a request" id="add-file-modal-button-disabled" %}
+              Add File to Request
+            {% /button %}
+          {% endif %}
+        {% elif is_author %}
+          <form action="" method="POST">
+            {% csrf_token %}
+            {% #button type="submit" tooltip="Remove this file from this request" variant="warning" %}Remove File from Request{% /button %}
+          </form>
+        {% elif is_output_checker %}
+          {% #button variant="primary" type="link" href=path_item.download_url id="download-button" %}Download file{% /button %}
         {% endif %}
-      {% elif is_author %}
-        <form action="" method="POST">
-          {% csrf_token %}
-          {% #button type="submit" tooltip="Remove this file from this request" variant="warning" %}Remove File from Request{% /button %}
-        </form>
-      {% elif is_output_checker %}
-        {% #button variant="primary" type="link" href=path_item.download_url id="download-button" %}Download file{% /button %}
-      {% endif %}
+        {% #button variant="primary" type="link" href=path_item.contents_url external=True id="view-button" %}View ↗{% /button %}
+      </div>
     {% endfragment %}
 
     {% #card title=path_item.name container=True custom_button=add_button %}
 
       <div class="content">
-        {% if path_item.display_type == "iframe" %}
-          <iframe
-            src="{{ path_item.contents_url }}"
-            title="{{ path_item.relpath }}"
-            frameborder=0
-            height=1000
-            style="width: 100%;"
-          >
-          </iframe>
-        {% elif path_item.display_type == "image" %}
-          <div class="content-scroller">
-            <img src="{{ path_item.contents_url }}">
-          </div>
-        {% elif path_item.display_type == "table" %}
-          <div class="content-scroller">
-            {% include "file_browser/csv.html" with contents=path_item.contents %}
-          </div>
-        {% else %}
-          <div class="content-scroller">
-                <pre>{{ path_item.contents }}</pre>
-          </div>
-        {% endif %}
+        <iframe src="{{ path_item.contents_url }}"
+                title="{{ path_item.relpath }}"
+                frameborder=0
+                height=1000
+                style="width: 100%;"
+        />
       </div>
     {% /card %}
 
diff --git a/airlock/templates/file_browser/csv.html b/airlock/templates/file_browser/csv.html
index 7ecc7d55..7fa3053d 100644
--- a/airlock/templates/file_browser/csv.html
+++ b/airlock/templates/file_browser/csv.html
@@ -1,17 +1,28 @@
-{% load airlocktags %}
-{% as_csv_data contents as csv_data %}
-<div id="csvtable" class="inline-block min-w-full align-middle max-w-full">
+<style>
+  .datatable thead {
+    position: sticky;
+    top: 0;
+    text-align: left;
+    background-color: rgba(248,250,252);
+  }
+
+  .datatable tbody tr:nth-child(even) {
+    background-color: rgba(248,250,252);
+  }
+</style>
+
+<div id="csvtable">
   <p class="spinner">Loading table data...</p>
   <table class="datatable" style="display: none">
-    <thead class="bg-slate-200" id="csvTable">
+    <thead>
       <tr>
-        {% for header in csv_data.headers %}
+        {% for header in headers %}
           <th>{{ header }}</th>
         {% endfor %}
       </tr>
     </thead>
     <tbody>
-      {% for row in csv_data.rows %}
+      {% for row in rows %}
         <tr>
           {% for cell in row %}
             <td>{{ cell }}</td>
diff --git a/airlock/templates/file_browser/index.html b/airlock/templates/file_browser/index.html
index 8d7feb98..f02622d7 100644
--- a/airlock/templates/file_browser/index.html
+++ b/airlock/templates/file_browser/index.html
@@ -61,17 +61,6 @@
       overflow: scroll;
     }
 
-    .datatable thead {
-      position: sticky;
-      top: 0;
-      text-align: left;
-    }
-
-    .datatable tbody tr:nth-child(even) {
-      background-color: rgba(248,250,252);
-    }
-
-
   </style>
 {% endblock extra_styles %}
 
diff --git a/airlock/templates/file_browser/text.html b/airlock/templates/file_browser/text.html
new file mode 100644
index 00000000..a169eaa0
--- /dev/null
+++ b/airlock/templates/file_browser/text.html
@@ -0,0 +1,3 @@
+<pre class="{{ class }}">
+{{ text }}
+</pre>
diff --git a/airlock/templatetags/__init__.py b/airlock/templatetags/__init__.py
deleted file mode 100644
index e69de29b..00000000
diff --git a/airlock/templatetags/airlocktags.py b/airlock/templatetags/airlocktags.py
deleted file mode 100644
index 1124d40c..00000000
--- a/airlock/templatetags/airlocktags.py
+++ /dev/null
@@ -1,15 +0,0 @@
-import csv
-
-from django import template
-
-
-register = template.Library()
-
-
-@register.simple_tag
-def as_csv_data(file_content):
-    reader = csv.reader(file_content.splitlines(keepends=True))
-    return {
-        "headers": next(reader),
-        "rows": list(reader),
-    }
diff --git a/airlock/views/helpers.py b/airlock/views/helpers.py
index b8446694..b7ad08c9 100644
--- a/airlock/views/helpers.py
+++ b/airlock/views/helpers.py
@@ -1,9 +1,18 @@
-from email.utils import formatdate
+import csv
+import functools
+from email.utils import formatdate, parsedate
+from pathlib import Path
 
 from django.core.exceptions import PermissionDenied
-from django.http import FileResponse, Http404
+from django.http import FileResponse, Http404, HttpResponseNotModified
+from django.template import loader
+from django.template.response import SimpleTemplateResponse
 
-from airlock.business_logic import bll
+from airlock.business_logic import UrlPath, bll
+
+
+class ServeFileException(Exception):
+    pass
 
 
 def login_exempt(view):
@@ -35,16 +44,104 @@ def get_release_request_or_raise(user, request_id):
     return release_request
 
 
-def serve_file(abspath, download=False, filename=None):
-    stat = abspath.stat()
-    # use same ETag format as whitenoise
-    headers = {
-        "Last-Modified": formatdate(stat.st_mtime, usegmt=True),
-        "ETag": f'"{int(stat.st_mtime):x}-{stat.st_size:x}"',
+def download_file(abspath, filename=None):
+    """Simple Helper to download file."""
+    return FileResponse(abspath.open("rb"), as_attachment=True, filename=filename)
+
+
+def render_with_template(template):
+    """Micro framework for rendering content.
+
+    The main purpose is to be able to check to see if the template has changed
+    ahead of calling the render function and doing the work.
+
+    It loads the template path used, and stores it on the wrapper function
+    object for later inspection.
+    """
+    django_template = loader.get_template(template)
+    template_path = Path(django_template.template.origin.name)
+
+    def decorator(func):
+        @functools.wraps(func)
+        def wrapper(abspath, suffix):
+            context = func(abspath, suffix)
+            return SimpleTemplateResponse(template, context)
+
+        wrapper.template_path = template_path
+
+        return wrapper
+
+    return decorator
+
+
+@render_with_template("file_browser/csv.html")
+def csv_renderer(abspath, suffix):
+    reader = csv.reader(abspath.open())
+    headers = next(reader)
+    return {"headers": headers, "rows": reader}
+
+
+@render_with_template("file_browser/text.html")
+def text_renderer(abspath, suffix):
+    return {
+        "text": abspath.read_text(),
+        "class": suffix.lstrip("."),
     }
-    return FileResponse(
-        abspath.open("rb"),
-        headers=headers,
-        as_attachment=download,
-        filename=filename,
-    )
+
+
+FILE_RENDERERS = {
+    ".csv": csv_renderer,
+    ".log": text_renderer,
+    ".txt": text_renderer,
+    ".json": text_renderer,
+}
+
+
+def build_etag(content_stat, template=None):
+    # Like whitenoise, use filesystem metadata rather than hash as its faster
+    etag = f"{int(content_stat.st_mtime):x}-{content_stat.st_size:x}"
+    if template:
+        # add the renderer's template etag so cache is invalidated if we change it
+        template_stat = Path(template).stat()
+        etag = f"{etag}-{int(template_stat.st_mtime):x}-{template_stat.st_size:x}"
+
+    # quote as per spec
+    return f'"{etag}"'
+
+
+def serve_file(request, abspath, filename=None):
+    """Serve file contents in a form the browser can render.
+
+    For html and images, just serve directly.
+
+    For csv and text, render that to html then serve.
+    """
+    if filename:
+        suffix = UrlPath(filename).suffix
+    else:
+        suffix = abspath.suffix
+
+    if not suffix:
+        raise ServeFileException(
+            f"Cannot serve file {abspath}, filename {filename}, as there is no suffix on either"
+        )
+
+    renderer = FILE_RENDERERS.get(suffix)
+    stat = abspath.stat()
+    last_modified = formatdate(stat.st_mtime, usegmt=True)
+    etag = build_etag(stat, getattr(renderer, "template_path", None))
+    last_requested = request.headers.get("If-Modified-Since")
+
+    if request.headers.get("If-None-Match") == etag:
+        response = HttpResponseNotModified()
+    elif last_requested and parsedate(last_requested) >= parsedate(last_modified):
+        response = HttpResponseNotModified()
+    elif renderer:
+        response = renderer(abspath, suffix)
+    else:
+        response = FileResponse(abspath.open("rb"), filename=filename)
+
+    response.headers["Last-Modified"] = last_modified
+    response.headers["ETag"] = etag
+
+    return response
diff --git a/airlock/views/request.py b/airlock/views/request.py
index 71fa346b..41418d0d 100644
--- a/airlock/views/request.py
+++ b/airlock/views/request.py
@@ -12,7 +12,7 @@
 from airlock.business_logic import Status, bll
 from airlock.file_browser_api import get_request_tree
 
-from .helpers import get_release_request_or_raise, serve_file
+from .helpers import download_file, get_release_request_or_raise, serve_file
 
 
 def request_index(request):
@@ -104,13 +104,15 @@ def request_contents(request, request_id: str, path: str):
     # Downloads are only allowed for output checkers
     # Downloads are not allowed for request authors (including those that are also
     # output checkers)
-    if download and (
-        not request.user.output_checker
-        or (release_request.author == request.user.username)
-    ):
-        raise PermissionDenied()
+    if download:
+        if not request.user.output_checker or (
+            release_request.author == request.user.username
+        ):
+            raise PermissionDenied()
 
-    return serve_file(abspath, download, filename=path)
+        return download_file(abspath, filename=path)
+
+    return serve_file(request, abspath, filename=path)
 
 
 @require_http_methods(["POST"])
diff --git a/airlock/views/workspace.py b/airlock/views/workspace.py
index 353f7be9..9341ff96 100644
--- a/airlock/views/workspace.py
+++ b/airlock/views/workspace.py
@@ -107,7 +107,7 @@ def workspace_contents(request, workspace_name: str, path: str):
     if not abspath.is_file():
         return HttpResponseBadRequest()
 
-    return serve_file(abspath)
+    return serve_file(request, abspath)
 
 
 @require_http_methods(["POST"])
diff --git a/pyproject.toml b/pyproject.toml
index 76698d65..aa7cc48f 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -31,7 +31,8 @@ branch = true
 # Required to get full coverage when using Playwright
 concurrency = ["greenlet", "thread"]
 plugins = ["django_coverage_plugin"]
-omit = ["*/assets/*",]
+omit = ["*/assets/*"]
+
 
 [tool.coverage.report]
 fail_under = 100
diff --git a/tests/functional/test_e2e.py b/tests/functional/test_e2e.py
index 0d329579..c549f428 100644
--- a/tests/functional/test_e2e.py
+++ b/tests/functional/test_e2e.py
@@ -69,8 +69,9 @@ def test_e2e_release_files(page, live_server, dev_users, release_files_stubber):
     Test full Airlock process to create, submit and release files
     """
     # set up a workspace file in a subdirectory
+    workspace = factories.create_workspace("test-workspace")
     factories.write_workspace_file(
-        "test-workspace", "subdir/file.txt", "I am the file content"
+        workspace, "subdir/file.txt", "I am the file content"
     )
 
     # Log in as a researcher
@@ -92,7 +93,10 @@ def test_e2e_release_files(page, live_server, dev_users, release_files_stubber):
     # Click on the first link we find
     find_and_click(page.get_by_role("link", name="subdir").first)
     find_and_click(page.get_by_role("link", name="file.txt").first)
-    expect(page.locator("body")).to_contain_text("I am the file content")
+
+    expect(page.locator("iframe")).to_have_attribute(
+        "src", workspace.get_contents_url("subdir/file.txt")
+    )
 
     # Add file to request, with custom named group
     # Find the add file button and click on it to open the modal
@@ -106,7 +110,9 @@ def test_e2e_release_files(page, live_server, dev_users, release_files_stubber):
     expect(page).to_have_url(
         f"{live_server.url}/workspaces/view/test-workspace/subdir/file.txt"
     )
-    expect(page.locator("body")).to_contain_text("I am the file content")
+    expect(page.locator("iframe")).to_have_attribute(
+        "src", workspace.get_contents_url("subdir/file.txt")
+    )
 
     # The "Add file to request" button is disabled
     add_file_button = page.locator("#add-file-modal-button-disabled")
@@ -119,6 +125,7 @@ def test_e2e_release_files(page, live_server, dev_users, release_files_stubber):
     expect(page).to_have_url(url_regex)
     # get the request ID for the just-created request, for later reference
     request_id = url_regex.match(page.url).groups()[0]
+    release_request = bll.get_release_request(request_id, admin_user)
 
     # Find the filegroup in the tree
     # Note: `get_by_role`` gets all links on the page; `locator` searches
@@ -142,7 +149,10 @@ def test_e2e_release_files(page, live_server, dev_users, release_files_stubber):
 
     # Tree opens fully expanded, so now the file (in its subdir) is visible
     find_and_click(file_link)
-    expect(page.locator("body")).to_contain_text("I am the file content")
+
+    expect(page.locator("iframe")).to_have_attribute(
+        "src", release_request.get_contents_url("my-new-group/subdir/file.txt")
+    )
 
     # Submit request
     submit_button = page.locator("#submit-for-review-button")
@@ -186,7 +196,9 @@ def test_e2e_release_files(page, live_server, dev_users, release_files_stubber):
     # Click to open the filegroup tree
     find_and_click(filegroup_link)
     find_and_click(file_link)
-    expect(page.locator("body")).to_contain_text("I am the file content")
+    expect(page.locator("iframe")).to_have_attribute(
+        "src", release_request.get_contents_url("my-new-group/subdir/file.txt")
+    )
 
     # Download the file
     with page.expect_download() as download_info:
diff --git a/tests/integration/views/test_helpers.py b/tests/integration/views/test_helpers.py
index eb355f1b..d07a11b7 100644
--- a/tests/integration/views/test_helpers.py
+++ b/tests/integration/views/test_helpers.py
@@ -1,16 +1,95 @@
 import os
 
+import pytest
+
 from airlock.views import helpers
 
 
-def test_serve_file(tmp_path):
-    path = tmp_path / "test.txt"
-    path.write_text("hi")
+@pytest.mark.parametrize(
+    "suffix,mimetype,template_path",
+    [
+        (".html", "text/html", None),
+        (".png", "image/png", None),
+        (".csv", "text/html", "airlock/templates/file_browser/csv.html"),
+        (".txt", "text/html", "airlock/templates/file_browser/text.html"),
+    ],
+)
+def test_serve_file_rendered(tmp_path, rf, suffix, mimetype, template_path):
+    path = tmp_path / ("test" + suffix)
+    # use a csv as test data, it works for other types too
+    path.write_text("a,b,c\n1,2,3")
+
+    time = 1709652904  # date this test was written
+    os.utime(path, (time, time))
+
+    etag = helpers.build_etag(path.stat(), template_path)
+
+    response = helpers.serve_file(rf.get("/"), path)
+    if hasattr(response, "render"):
+        # ensure template is actually rendered, for template coverage
+        response.render()
+
+    assert response.status_code == 200
+    assert response.headers["Last-Modified"] == "Tue, 05 Mar 2024 15:35:04 GMT"
+    assert response.headers["Content-Type"].split(";")[0] == mimetype
+    assert response.headers["Etag"] == etag
+
+
+def test_serve_file_rendered_with_filename(tmp_path, rf):
+    path = tmp_path / "hash"
+    path.write_text("data")
+
     time = 1709652904  # date this test was written
     os.utime(path, (time, time))
 
-    response = helpers.serve_file(path)
+    response = helpers.serve_file(rf.get("/"), path, filename="test.html")
+    assert response.status_code == 200
     assert response.headers["Last-Modified"] == "Tue, 05 Mar 2024 15:35:04 GMT"
-    assert response.headers["Etag"] == '"65e73ba8-2"'
-    assert response.headers["Content-Type"] == "text/plain"
-    assert response.headers["Content-Length"] == "2"
+    assert response.headers["Content-Type"].split(";")[0] == "text/html"
+    assert response.headers["Etag"] == '"65e73ba8-4"'
+
+
+@pytest.mark.parametrize(
+    "suffix,template_path",
+    [
+        (".html", None),
+        (".png", None),
+        (".csv", "airlock/templates/file_browser/csv.html"),
+        (".txt", "airlock/templates/file_browser/text.html"),
+    ],
+)
+def test_serve_file_not_modified(tmp_path, rf, suffix, template_path):
+    path = tmp_path / ("test" + suffix)
+    # use a csv as test data, it renders fine as text
+    path.write_text("a,b,c\n1,2,3")
+    time = 1709652904  # date this test was written
+    os.utime(path, (time, time))
+
+    etag = helpers.build_etag(path.stat(), template_path)
+
+    request = rf.get("/", headers={"If-None-Match": etag})
+    response = helpers.serve_file(request, path)
+    assert response.status_code == 304
+
+    request = rf.get(
+        "/", headers={"If-Modified-Since": "Tue, 05 Mar 2024 15:35:04 GMT"}
+    )
+    response = helpers.serve_file(request, path)
+    assert response.status_code == 304
+
+    request = rf.get(
+        "/", headers={"If-Modified-Since": "Tue, 05 Mar 2023 15:35:04 GMT"}
+    )
+    response = helpers.serve_file(request, path)
+    assert response.status_code == 200
+
+
+def test_serve_file_no_suffix(tmp_path, rf):
+    path = tmp_path / "nosuffix"
+    path.touch()
+
+    with pytest.raises(helpers.ServeFileException):
+        helpers.serve_file(rf.get("/"), path)
+
+    with pytest.raises(helpers.ServeFileException):
+        helpers.serve_file(rf.get("/"), path, filename="nosuffix")
diff --git a/tests/integration/views/test_request.py b/tests/integration/views/test_request.py
index 6fb19bfd..79b54c6f 100644
--- a/tests/integration/views/test_request.py
+++ b/tests/integration/views/test_request.py
@@ -53,7 +53,9 @@ def test_request_view_with_file(airlock_client):
     factories.write_request_file(release_request, "group", "file.txt", "foobar")
     response = airlock_client.get(f"/requests/view/{release_request.id}/group/file.txt")
     assert response.status_code == 200
-    assert "foobar" in response.rendered_content
+    assert (
+        release_request.get_contents_url("group/file.txt") in response.rendered_content
+    )
     assert response.template_name == "file_browser/index.html"
 
 
@@ -66,7 +68,9 @@ def test_request_view_with_file_htmx(airlock_client):
         headers={"HX-Request": "true"},
     )
     assert response.status_code == 200
-    assert "foobar" in response.rendered_content
+    assert (
+        release_request.get_contents_url("group/file.txt") in response.rendered_content
+    )
     assert response.template_name == "file_browser/contents.html"
     assert '<ul id="tree"' not in response.rendered_content
 
@@ -147,8 +151,7 @@ def test_request_contents_file(airlock_client):
     )
     response = airlock_client.get("/requests/content/id/default/file.txt")
     assert response.status_code == 200
-    assert not response.as_attachment
-    assert list(response.streaming_content) == [b"test"]
+    assert response.content == b'<pre class="txt">\ntest\n</pre>\n'
 
 
 def test_request_contents_dir(airlock_client):
diff --git a/tests/integration/views/test_workspace.py b/tests/integration/views/test_workspace.py
index 3411a0cd..2e5d0429 100644
--- a/tests/integration/views/test_workspace.py
+++ b/tests/integration/views/test_workspace.py
@@ -50,22 +50,24 @@ def test_workspace_view_with_directory(airlock_client):
 
 def test_workspace_view_with_file(airlock_client):
     airlock_client.login(output_checker=True)
-    factories.write_workspace_file("workspace", "file.txt", "foobar")
+    workspace = factories.create_workspace("workspace")
+    factories.write_workspace_file(workspace, "file.txt", "foobar")
     response = airlock_client.get("/workspaces/view/workspace/file.txt")
     assert response.status_code == 200
-    assert "foobar" in response.rendered_content
+    assert workspace.get_contents_url("file.txt") in response.rendered_content
     assert response.template_name == "file_browser/index.html"
     assert "HX-Request" in response.headers["Vary"]
 
 
 def test_workspace_view_with_file_htmx(airlock_client):
     airlock_client.login(output_checker=True)
-    factories.write_workspace_file("workspace", "file.txt", "foobar")
+    workspace = factories.create_workspace("workspace")
+    factories.write_workspace_file(workspace, "file.txt", "foobar")
     response = airlock_client.get(
         "/workspaces/view/workspace/file.txt", headers={"HX-Request": "true"}
     )
     assert response.status_code == 200
-    assert "foobar" in response.rendered_content
+    assert workspace.get_contents_url("file.txt") in response.rendered_content
     assert response.template_name == "file_browser/contents.html"
     assert '<ul id="tree"' not in response.rendered_content
     assert "HX-Request" in response.headers["Vary"]
@@ -126,10 +128,10 @@ def test_workspace_view_with_svg_file(airlock_client):
 
 def test_workspace_view_with_csv_file(airlock_client):
     airlock_client.login(output_checker=True)
-    factories.write_workspace_file("workspace", "file.csv", "header1,header2\nFoo,Bar")
+    workspace = factories.create_workspace("workspace")
+    factories.write_workspace_file(workspace, "file.csv", "header1,header2\nFoo,Bar")
     response = airlock_client.get("/workspaces/view/workspace/file.csv")
-    for content in ["<table", "Foo", "Bar"]:
-        assert content in response.rendered_content
+    assert workspace.get_contents_url("file.csv") in response.rendered_content
 
 
 def test_workspace_view_with_404(airlock_client):
@@ -214,7 +216,7 @@ def test_workspace_contents_file(airlock_client):
     factories.write_workspace_file("workspace", "file.txt", "test")
     response = airlock_client.get("/workspaces/content/workspace/file.txt")
     assert response.status_code == 200
-    assert list(response.streaming_content) == [b"test"]
+    assert response.content == b'<pre class="txt">\ntest\n</pre>\n'
 
 
 def test_workspace_contents_dir(airlock_client):
diff --git a/tests/unit/test_templatetags.py b/tests/unit/test_templatetags.py
deleted file mode 100644
index 9cca262a..00000000
--- a/tests/unit/test_templatetags.py
+++ /dev/null
@@ -1,9 +0,0 @@
-from airlock.templatetags.airlocktags import as_csv_data
-
-
-def test_file_content_as_csv_data():
-    content = "Header1,Header2,Header3\n" "One,Two,Three\n" "Four,Five,Six\n"
-    assert as_csv_data(content) == {
-        "headers": ["Header1", "Header2", "Header3"],
-        "rows": [["One", "Two", "Three"], ["Four", "Five", "Six"]],
-    }