Add SOONG_SDK_SNAPSHOT_VERSION support

SOONG_SDK_SNAPSHOT_VERSION=current will generate unversioned and
versioned prebuilts and a versioned snapshot module. This is the
default behavior. The zip file containing the generated snapshot will
be <sdk name>-current.zip.

SOONG_SDK_SNAPSHOT_VERSION=unversioned will generate unversioned
prebuilts only and the zip file containing the generated snapshot will
be <sdk name>.zip.

SOONG_SDK_SNAPSHOT_VERSION=<number> will generate versioned prebuilts
and a versioned snapshot module only. The zip file containing the
generated snapshot will be <sdk name>-<number>.zip.

Bug: 157884619
Test: m nothing
      m SOONG_SDK_SNAPSHOT_VERSION=current art-module-sdk
      - check that the generated Android.bp file has not changed
        from the default.
      m SOONG_SDK_SNAPSHOT_VERSION=none art-module-sdk
      - check that the generated Android.bp file does not contain
        versioned modules.
      m SOONG_SDK_SNAPSHOT_VERSION=2 art-module-sdk
      - check that the generated Android.bp file only contains
        version 2 of each module.
Change-Id: I087e9d7d3ad110508a3d6a39bca50cbb46b3ce82
diff --git a/sdk/sdk_test.go b/sdk/sdk_test.go
index 12545d6..a13b0d7 100644
--- a/sdk/sdk_test.go
+++ b/sdk/sdk_test.go
@@ -564,4 +564,101 @@
 			`),
 		)
 	})
+
+	t.Run("SOONG_SDK_SNAPSHOT_VERSION=unversioned", func(t *testing.T) {
+		result := android.GroupFixturePreparers(
+			preparer,
+			android.FixtureMergeEnv(map[string]string{
+				"SOONG_SDK_SNAPSHOT_VERSION": "unversioned",
+			}),
+		).RunTest(t)
+
+		checkZipFile(t, result, "out/soong/.intermediates/mysdk/common_os/mysdk.zip")
+
+		CheckSnapshot(t, result, "mysdk", "",
+			checkAndroidBpContents(`
+// This is auto-generated. DO NOT EDIT.
+
+java_import {
+    name: "myjavalib",
+    prefer: false,
+    visibility: ["//visibility:public"],
+    apex_available: ["//apex_available:platform"],
+    jars: ["java/myjavalib.jar"],
+}
+			`),
+		)
+	})
+
+	t.Run("SOONG_SDK_SNAPSHOT_VERSION=current", func(t *testing.T) {
+		result := android.GroupFixturePreparers(
+			preparer,
+			android.FixtureMergeEnv(map[string]string{
+				"SOONG_SDK_SNAPSHOT_VERSION": "current",
+			}),
+		).RunTest(t)
+
+		checkZipFile(t, result, "out/soong/.intermediates/mysdk/common_os/mysdk-current.zip")
+
+		CheckSnapshot(t, result, "mysdk", "",
+			checkAndroidBpContents(`
+// This is auto-generated. DO NOT EDIT.
+
+java_import {
+    name: "mysdk_myjavalib@current",
+    sdk_member_name: "myjavalib",
+    visibility: ["//visibility:public"],
+    apex_available: ["//apex_available:platform"],
+    jars: ["java/myjavalib.jar"],
+}
+
+java_import {
+    name: "myjavalib",
+    prefer: false,
+    visibility: ["//visibility:public"],
+    apex_available: ["//apex_available:platform"],
+    jars: ["java/myjavalib.jar"],
+}
+
+sdk_snapshot {
+    name: "mysdk@current",
+    visibility: ["//visibility:public"],
+    java_header_libs: ["mysdk_myjavalib@current"],
+}
+			`),
+		)
+	})
+
+	t.Run("SOONG_SDK_SNAPSHOT_VERSION=2", func(t *testing.T) {
+		result := android.GroupFixturePreparers(
+			preparer,
+			android.FixtureMergeEnv(map[string]string{
+				"SOONG_SDK_SNAPSHOT_VERSION": "2",
+			}),
+		).RunTest(t)
+
+		checkZipFile(t, result, "out/soong/.intermediates/mysdk/common_os/mysdk-2.zip")
+
+		CheckSnapshot(t, result, "mysdk", "",
+			checkAndroidBpContents(`
+// This is auto-generated. DO NOT EDIT.
+
+java_import {
+    name: "mysdk_myjavalib@2",
+    sdk_member_name: "myjavalib",
+    visibility: ["//visibility:public"],
+    apex_available: ["//apex_available:platform"],
+    jars: ["java/myjavalib.jar"],
+}
+
+sdk_snapshot {
+    name: "mysdk@2",
+    visibility: ["//visibility:public"],
+    java_header_libs: ["mysdk_myjavalib@2"],
+}
+			`),
+			// A versioned snapshot cannot be used on its own so add the source back in.
+			snapshotTestPreparer(checkSnapshotWithoutSource, android.FixtureWithRootAndroidBp(bp)),
+		)
+	})
 }