flux diff artifact: Add (and fix) unit tests.

Signed-off-by: Florian Forster <fforster@gitlab.com>

cmd/flux/diff_artifact_test.go

@@ -22,6 +22,9 @@ package main
 import (
 	"context"
 	"fmt"
+	"io"
+	"os"
+	"path/filepath"
 	"testing"
 	"time"
 
@@ -65,6 +68,7 @@ func TestDiffArtifact(t *testing.T) {
 		argsTpl  string
 		pushFile string
 		diffFile string
+		diffName string
 		assert   assertFunc
 	}{
 		{
@@ -75,14 +79,50 @@ func TestDiffArtifact(t *testing.T) {
 			diffFile: "./testdata/diff-artifact/deployment.yaml",
 			assert:   assertGoldenFile("testdata/diff-artifact/success.golden"),
 		},
+		{
+			name:     "create unified diff output by default",
+			url:      "oci://%s/podinfo:2.0.0",
+			argsTpl:  "diff artifact %s --path=%s",
+			pushFile: "./testdata/diff-artifact/deployment.yaml",
+			diffFile: "./testdata/diff-artifact/deployment-diff.yaml",
+			diffName: "deployment.yaml",
+			assert: assert(
+				assertErrorIs(ErrDiffArtifactChanged),
+				assertRegexp(`(?m)^-            cpu: 1000m$`),
+				assertRegexp(`(?m)^\+            cpu: 2000m$`),
+			),
+		},
 		{
 			name:     "should fail if there is a diff",
 			url:      "oci://%s/podinfo:2.0.0",
 			argsTpl:  "diff artifact %s --path=%s",
 			pushFile: "./testdata/diff-artifact/deployment.yaml",
 			diffFile: "./testdata/diff-artifact/deployment-diff.yaml",
-			assert:   assertErrorIs(ErrDiffArtifactChanged),
+			diffName: "only-local.yaml",
+			assert: assert(
+				assertErrorIs(ErrDiffArtifactChanged),
+				assertRegexp(`(?m)^Only in [^:]+: deployment.yaml$`),
+				assertRegexp(`(?m)^Only in [^:]+: only-local.yaml$`),
+			),
 		},
+		{
+			name:     "semantic diff using dyff",
+			url:      "oci://%s/podinfo:2.0.0",
+			argsTpl:  "diff artifact %s --path=%s --differ=dyff",
+			pushFile: "./testdata/diff-artifact/deployment.yaml",
+			diffFile: "./testdata/diff-artifact/deployment-diff.yaml",
+			diffName: "deployment.yaml",
+			assert: assert(
+				assertErrorIs(ErrDiffArtifactChanged),
+				assertRegexp(`(?m)^spec.template.spec.containers.podinfod.resources.limits.cpu$`),
+				assertRegexp(`(?m)^  ± value change$`),
+				assertRegexp(`(?m)^    - 1000m$`),
+				assertRegexp(`(?m)^    \+ 2000m$`),
+			),
+		},
+		// Attention: tests do not spawn a new process when executing commands.
+		// That means that the --differ flag remains set to "dyff" for
+		// subsequent tests.
 	}
 
 	ctx := ctrl.SetupSignalHandler()
@@ -99,11 +139,38 @@ func TestDiffArtifact(t *testing.T) {
 				t.Fatalf(fmt.Errorf("failed to push image: %w", err).Error())
 			}
 
+			diffFile := tt.diffFile
+			if tt.diffName != "" {
+				diffFile = makeTempFile(t, tt.diffFile, tt.diffName)
+			}
+
 			cmd := cmdTestCase{
-				args:   fmt.Sprintf(tt.argsTpl, tt.url, tt.diffFile),
+				args:   fmt.Sprintf(tt.argsTpl, tt.url, diffFile),
 				assert: tt.assert,
 			}
 			cmd.runTestCmd(t)
 		})
 	}
 }
+
+func makeTempFile(t *testing.T, source, basename string) string {
+	path := filepath.Join(t.TempDir(), basename)
+	out, err := os.Create(path)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer out.Close()
+
+	in, err := os.Open(source)
+	if err != nil {
+		t.Fatal(err)
+	}
+	defer in.Close()
+
+	_, err = io.Copy(out, in)
+	if err != nil {
+		t.Fatal(err)
+	}
+
+	return path
+}

cmd/flux/main_test.go

@@ -26,6 +26,7 @@ import (
 	"io"
 	"os"
 	"path/filepath"
+	"regexp"
 	"strings"
 	"sync/atomic"
 	"testing"
@@ -338,6 +339,17 @@ func assertGoldenTemplateFile(goldenFile string, templateValues map[string]strin
 		})
 }
 
+func assertRegexp(expected string) assertFunc {
+	re := regexp.MustCompile(expected)
+
+	return func(output string, _ error) error {
+		if !re.MatchString(output) {
+			return fmt.Errorf("Output does not match regular expression:\nOutput:\n%s\n\nRegular expression:\n%s", output, expected)
+		}
+		return nil
+	}
+}
+
 type TestClusterMode int
 
 const (

cmd/flux/testdata/diff-artifact/deployment-diff.yaml

@@ -4,7 +4,7 @@ metadata:
   labels:
       kustomize.toolkit.fluxcd.io/name: podinfo
       kustomize.toolkit.fluxcd.io/namespace: {{ .fluxns }}
-  name: podinfo-diff
+  name: podinfo
   namespace: default
 spec:
   minReadySeconds: 3

cmd/flux/testdata/diff-artifact/deployment.yaml

@@ -71,7 +71,7 @@ spec:
           timeoutSeconds: 5
         resources:
           limits:
-            cpu: 2000m
+            cpu: 1000m
             memory: 512Mi
           requests:
             cpu: 100m