Add E2E for data-values-file reading a dir

examples/data-values-directory/README.md

@@ -0,0 +1,23 @@
+This example demonstrates how ytt handles specifying a directory for Data Values
+inputs. (originally https://kubernetes.slack.com/archives/CH8KCCKA5/p1651167583289939)
+
+With this:
+```
+├── config
+│   ├── config.yml
+│   └── values-schema.yml
+└── values                   <-- any YAML under here is assumed to be plain Data Values
+    ├── appdev-overrides     <-- sorted by full pathname, alphabetically
+    │   └── values.yaml
+    └── operator-overrides
+        ├── 50-operations-overrides.yml
+        ├── 99-opssec-overrides.yml
+        └── approvals.toml   <-- non YAML files are ignored.
+```
+
+Executing this:
+
+```console
+$ ytt -f examples/data-values-directory/config.yml \
+      --data-values-file examples/data-values-directory/values/
+```

examples/data-values-directory/config/config.yml

@@ -0,0 +1,8 @@
+#! In the real-world, this configuration would be the manifests that describe
+#! this application's deployment. For this example, we simply render the
+#! net values; this is the point of this example.
+
+#@ load("@ytt:data", "data")
+
+---
+values: #@ data.values

examples/data-values-directory/config/values-schema.yml

@@ -0,0 +1,10 @@
+#@data/values-schema
+---
+name: suggestion-service
+instances: 0
+accept_insecure_conns: true
+#@schema/nullable
+cache:
+  driver: ""
+  #@schema/type any=True
+  config: {}

examples/data-values-directory/run.sh

@@ -0,0 +1,6 @@
+#!/usr/bin/env bash
+
+set -e
+
+./ytt -f examples/data-values-directory/config/ \
+      --data-values-file examples/data-values-directory/values/

examples/data-values-directory/values/appdev-overrides/values.yaml

@@ -0,0 +1,8 @@
+---
+instances: 1
+accept_insecure_conns: true
+cache:
+  driver: in-memory
+  config:
+    maxEntries: 1024
+    strategy: MRU

examples/data-values-directory/values/operator-overrides/50-operations-overrides.yml

@@ -0,0 +1,10 @@
+---
+# 2022-05-13: avg + rms over last 3 months
+instances: 4
+
+cache:
+  driver: redis
+  config:
+    host: localhost:6379
+    tls-client-cert-file: client.crt
+    tls-client-key-file: client.key

examples/data-values-directory/values/operator-overrides/99-opssec-overrides.yml

@@ -0,0 +1,3 @@
+---
+# Policy 1.31a: all north-south connections must be encrypted.
+accept_insecure_conns: false

examples/data-values-directory/values/operator-overrides/approvals.toml

@@ -0,0 +1,7 @@
+[[approvals]]
+    dept = "operations"
+    user = "[email protected]"
+
+[[approvals]]
+    dept = "Operations Security"
+    user = "[email protected]"

test/e2e/e2e_test.go

@@ -104,6 +104,18 @@ float: 123.123
 
 			require.Equal(t, expectedOutput, actualOutput)
 		})
+		t.Run("--data-values-file enumerates YAML files from given directory", func(t *testing.T) {
+			testDir := "../../examples/data-values-directory"
+			flags := yttFlags{
+				{"--data-values-file": testDir + "/values"},
+			}
+			actualOutput := runYtt(t, testInputFiles{testDir + "/config"}, "", flags, nil)
+
+			expectedOutput, err := ioutil.ReadFile(filepath.Join(testDir, "expected.txt"))
+			require.NoError(t, err)
+
+			require.Equal(t, string(expectedOutput), actualOutput)
+		})
 	})
 	t.Run("can be 'required'", func(t *testing.T) {
 		expectedFileOutput, err := ioutil.ReadFile("../../examples/data-values-required/expected.txt")