Initial provider implementation (#18)

This brings over the initial buildx prototype from pulumi/pulumi-docker
and fixes various build and release issues.

provider/internal/dockerfile_test.go

@@ -0,0 +1,102 @@
+// Copyright 2024, Pulumi Corporation.
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package internal
+
+import (
+	"testing"
+
+	"github.com/stretchr/testify/assert"
+)
+
+func TestValidateDockerfile(t *testing.T) {
+	t.Parallel()
+	tests := []struct {
+		name    string
+		d       Dockerfile
+		givenC  Context
+		preview bool
+
+		wantErr string
+	}{
+		{
+			name: "relative",
+			d: Dockerfile{
+				Location: "../internal/../internal/testdata/noop/Dockerfile",
+			},
+		},
+		{
+			name: "missing file",
+			d: Dockerfile{
+				Location: "/does/not/exist/Dockerfile",
+			},
+			wantErr: "no such file",
+		},
+		{
+			name: "invalid syntax",
+			d: Dockerfile{
+				Location: "testdata/Dockerfile.invalid",
+			},
+			wantErr: "unknown instruction: RUNN",
+		},
+		{
+			name: "invalid syntax inline",
+			d: Dockerfile{
+				Inline: "RUNN it",
+			},
+			wantErr: "unknown instruction: RUNN",
+		},
+		{
+			name: "valid syntax inline",
+			d: Dockerfile{
+				Inline: "FROM scratch",
+			},
+		},
+		{
+			name:    "unset",
+			d:       Dockerfile{},
+			wantErr: "missing 'location' or 'inline'",
+		},
+		{
+			name:   "unset with remote context",
+			d:      Dockerfile{},
+			givenC: Context{Location: "https://github.com/foobar"},
+		},
+		{
+			name:    "preview",
+			d:       Dockerfile{},
+			preview: true,
+		},
+		{
+			name:    "over-specified",
+			d:       Dockerfile{Location: ".", Inline: "FROM scratch"},
+			wantErr: `only specify "file" or "inline", not both`,
+		},
+	}
+
+	for _, tt := range tests {
+		tt := tt
+		t.Run(tt.name, func(t *testing.T) {
+			t.Parallel()
+
+			err := tt.d.validate(tt.preview, &tt.givenC)
+
+			if tt.wantErr == "" {
+				assert.NoError(t, err)
+			} else {
+				assert.ErrorContains(t, err, tt.wantErr)
+			}
+		})
+	}
+}