rpc/core: more docs and a test for /blockchain endpoint (#5417)

Closes #5339

rpc/client/rpc_test.go

@@ -302,6 +302,36 @@ func TestAppCalls(t *testing.T) {
 	}
 }
 
+func TestBlockchainInfo(t *testing.T) {
+	for i, c := range GetClients() {
+		err := client.WaitForHeight(c, 10, nil)
+		require.NoError(t, err)
+
+		res, err := c.BlockchainInfo(context.Background(), 0, 0)
+		require.Nil(t, err, "%d: %+v", i, err)
+		assert.True(t, res.LastHeight > 0)
+		assert.True(t, len(res.BlockMetas) > 0)
+
+		res, err = c.BlockchainInfo(context.Background(), 1, 1)
+		require.Nil(t, err, "%d: %+v", i, err)
+		assert.True(t, res.LastHeight > 0)
+		assert.True(t, len(res.BlockMetas) == 1)
+
+		res, err = c.BlockchainInfo(context.Background(), 1, 10000)
+		require.Nil(t, err, "%d: %+v", i, err)
+		assert.True(t, res.LastHeight > 0)
+		assert.True(t, len(res.BlockMetas) < 100)
+		for _, m := range res.BlockMetas {
+			assert.NotNil(t, m)
+		}
+
+		res, err = c.BlockchainInfo(context.Background(), 10000, 1)
+		require.NotNil(t, err)
+		assert.Nil(t, res)
+		assert.Contains(t, err.Error(), "can't be greater than max")
+	}
+}
+
 func TestBroadcastTxSync(t *testing.T) {
 	require := require.New(t)
 

rpc/core/blocks.go

@@ -10,11 +10,18 @@ import (
 )
 
 // BlockchainInfo gets block headers for minHeight <= height <= maxHeight.
-// Block headers are returned in descending order (highest first).
+//
+// If maxHeight does not yet exist, blocks up to the current height will be
+// returned. If minHeight does not exist (due to pruning), earliest existing
+// height will be used.
+//
+// At most 20 items will be returned. Block headers are returned in descending
+// order (highest first).
+//
 // More: https://docs.tendermint.com/master/rpc/#/Info/blockchain
 func BlockchainInfo(ctx *rpctypes.Context, minHeight, maxHeight int64) (*ctypes.ResultBlockchainInfo, error) {
-	// maximum 20 block metas
 	const limit int64 = 20
+
 	var err error
 	minHeight, maxHeight, err = filterMinMax(
 		env.BlockStore.Base(),
@@ -25,12 +32,14 @@ func BlockchainInfo(ctx *rpctypes.Context, minHeight, maxHeight int64) (*ctypes.
 	if err != nil {
 		return nil, err
 	}
-	env.Logger.Debug("BlockchainInfoHandler", "maxHeight", maxHeight, "minHeight", minHeight)
+	env.Logger.Debug("BlockchainInfo", "maxHeight", maxHeight, "minHeight", minHeight)
 
-	blockMetas := []*types.BlockMeta{}
+	blockMetas := make([]*types.BlockMeta, 0, maxHeight-minHeight+1)
 	for height := maxHeight; height >= minHeight; height-- {
 		blockMeta := env.BlockStore.LoadBlockMeta(height)
-		blockMetas = append(blockMetas, blockMeta)
+		if blockMeta != nil {
+			blockMetas = append(blockMetas, blockMeta)
+		}
 	}
 
 	return &ctypes.ResultBlockchainInfo{

rpc/openapi/openapi.yaml

@@ -625,7 +625,12 @@ paths:
       description: |
         Get block headers for minHeight <= height maxHeight.
 
-        At most 20 items will be returned.
+        If maxHeight does not yet exist, blocks up to the current height will
+        be returned. If minHeight does not exist (due to pruning), earliest
+        existing height will be used.
+
+        At most 20 items will be returned. Block headers are returned in
+        descending order (highest first).
       responses:
         "200":
           description: Block headers, returned in descending order (highest first).